Countries as far away as Indonesia and Argentina send their best and brightest to the United States for what is considered a superior university education.

Now, economic instability in their home countries, especially oil producing nations, threatens to shorten the stay here for many of the 326,000 foreign students in the United States and curtail the flow of new arrivals.

Some of the nearly 9,000 foreign students in the District, one of the highest concentrations in the country, said they are selling possessions, disconnecting phones, giving up apartments and working in violation of student visa restrictions to stay and complete their studies.

Although none of the students interviewed said they were working, they said it was not uncommon for them to take on such cash paying jobs as cab drivers, security guards and waiters.

Foreign student enrollment historically has been tied to global politics and economics and, most recently, oil prices. One-third of the 326,000 foreign students come from OPEC countries, according to the Institute for International Education in New York.

Venezuela, where petrodollars once financed as many as l0,000 students, is the latest country with students suddenly facing currency devaluations, restrictions and long waits for money from home.

The drop in Iranian enrollment from 51,3l0 in l979-80 to 28,70l in l98l-82 underscored the vulnerability of foreign student revenue to such factors, university officials said.

At George Washington University, which received a

million endowment from the government of Iran in l974 and had large numbers of government-sponsored Iranian students throughout the l970s, the Iranian student population has dropped by about half from a high of about 600 in 1978 since the l979 revolution and subsequent breakdown of U.S.-Iranian relations.

American University, which last year organized three exchange programs that would have brought in l00 Mexican graduate students a year, saw those programs postponed after last summer's devaluation of the peso.

A subsector of the city's educational system that is seeing even more severe decreases in revenues is the city's English language schools, many of which prepare students for university study.

And the combined effects of dropping oil prices and triple digit inflation in such countries as Argentina and Brazil could further affect Washington area universities and language schools.

The U.S. Immigration and Naturalization Service reports about 8,900 student visa holders attend District universities. George Washington University has the largest number with 2,500; American, l,935; Howard, l,538; and Georgetown, l,l00.

About l,300 foreign students attend institutions in Northern Virginia, and about 8,500 study in Maryland, according to INS.

Some university budget directors said the Iranian exodus taught them not to rely on income from large concentrations of students from single countries. But because many foreign students chose their schools on the recommendations of fellow nationals, most universities have large pockets of students from individual countries.

American has 603 students from Venezuela, Mexico and Nigeria together. Howard's l,583 foreign students include 500 Nigerians, 200 Jamaicans and l60 Iranians. The 2,500 at George Washington include 390 Iranians, and tiny Southeastern University has 574 students from economically troubled Nigeria--one-third of its total student population.

Student visas prohibit these students from working off campus, and exceptions are only granted for students experiencing "unforseen economic difficulties," INS spokesman Russell D. Manchester said.

That definition, he said, does not necessarily include currency devaluations.

But the students, particularly those at more costly schools, say their countries' austerity measures were totally unexpected.

Carlos Bustillos, an international business student at AU, has sold his car and canceled summer school plans. He is sending his two children back to his native Acarigua, a small Venezuelan town where his father is a retired politician.

Bustillos and his friends, fellow Venezuelans Eduardo Pulido, Alex Arcesilai and Gabriela Pardi, say they have not received money since Feb. l8, when the Venezuelan government implemented its new foreign currency restrictions and devalued its money, doubling the students cost of living here.

The government is still allowing them up to $490 a month at the old exchange rate, Bustillos explained. But they are all on a waiting list and haven't received any of that money since February.

All four have ruled out summer school; Pulido has given up his apartment and now rooms with a friend.

"We never would have come to such an expensive university if we had known this was going to happen," Pulido said.

Joseph Neale, director of American University's International Student Center, said his advisers counseled at least l00 Venezuelans last month, and that in the past year many of the university's Mexican students have had to either leave school or seek illegal employment.

"Those who work are very secretive about it," Neale said. Foreign students may work up to 20 hours a week on campus. But they said many find the small number of hours and minimum wage pay insufficient and are applying to the INS for full-time work permits.

The INS is responding to the students "on a case-to-case basis," said John Robichaud, government relations coordinator for the National Association for Foreign Student Affairs (NAFSA). "They're not just going to say, 'Okay, all Venezuelans can work full time,' " he said.

Robichaud and NAFSA information director Georgia Stewart said they see the INS' tightening of student visa regulations in the face of these currency shortages as inconsistent with U.S. international education policy.

"On one hand, the State Department, through AID (Agency for International Development) and the Caribbean Basin program, is handing out scholarships and inviting students to come here," Stewart said. But the INS is making it difficult for them to stay here, she added.

She said much of the controversy surrounding foreign students, particularly allegations that they violate their visa privileges, stems from the Iranian demonstrations of the late l970s and is unsubstantiated by statistics.

"The INS has such incomplete records that there is no way of knowing how many foreign students are in school, how many have left the country or how many of them are getting married," she said.

Manchester agreed that keeping track of foreign students is difficult because INS district offices only receive records of students first entering the country and not of foreign students who have transfered from schools in different districts.

A mass exodus of students who are from oil producing countries could affect the financial bases of universities in the District, including American, which receives $3 million a year from the 603 of its foreign students who come from oil producing countries, according to the campus newspaper, The Eagle.

These schools have had to weigh the short-term costs of allowing student payments to go uncollected against the long-term financial losses that would come with a decrease in foreign student enrollment.

Howard and Southeastern have allowed their Nigerian students to register without paying full tuition. Howard University Bursar Alfred Rascoe said that while the university has not suffered from the loss of Nigerian money, the future loss of Nigerian students "could have a significant effect" on university finances.

American University President Richard Berendzen said the school has not been able to make special allowances for foreign students. "It's just economically unfeasible," he said. "Even with groups of 50 students, you're talking about millions of dollars. A university just can't operate that way."

At Georgetown, foreign student adviser Eric Heiberg said most of his university's foreign students are relatively affluent, primarily European or Asian, and have not had difficulty paying their bills.

But Ronald Flowers, student affairs vice president at the University of the District of Columbia, which has 302 Nigerian and l83 Iranian students, said UDC has had to turn away a number of students who had not received their money on time. And, noted Flowers, those students pay higher, out-of-state rates.

Other schools affected by the students' money squeeze are those that teach English. One of the largest of those schools, ELS Language Center, 2129 S St. NW, where enrollment fluctuates between 60 and 120, has lost nearly all its Mexican students. Counselors there are scrambling to find work-study jobs and cheaper housing for the Venezuelans and Brazilians, officials say.

"I've had to tell some students, you'll just have to go home, you can't seem to be able to afford to stay here," ELS director Jane Tuckerman said. "And believe me, that really hurts."

Tuckerman views her school's current enrollment drop as a harbinger of problems to come in Washington area universities. "If this year it's English, next year it could be engineering," she said.

"While you don't see degree students going home in as great a number as English students, you're definitely going to see less and less of them coming over here to study."