The crowds still chanted "Architect, Architect" when Fernando Belaunde Terry, Peru's inveterate barnstormer of a president, recently whistle-stopped through the high Andean sierra where guerrillas have challenged his government.

In the presidential palace in Lima, where economic crisis hovers over ministers' meetings, the wooden tables of the old banquet room are still groaning with scale models of the bridges and apartment towers the architect has charted for the country.

But after months of recession, curtailed programs and resurgent political violence, Belaunde's hallmark formulas have begun to show troubling signs of wear. And two years after he reopened a new era of democratic government here, his government is facing what supporters call a crucial test.

"There were a lot of expectations raised by the return to democracy and the programs we initiated," said Jaime de Althaus, a top government policy adviser. "Now we run the risk of creating frustrations and having people lose confidence in democratic institutions."

Politicians and diplomats as yet see no prospect of a breakdown of democracy or a military coup like the one that ended Belaunde's first presidency in 1968. But signs of stress in this relatively poor country of 18 million are everywhere.

As recession has forced down prices of mineral exports like copper and silver to their lowest level in 40 years, Peru's economy has stalled and its balance of payments has slumped into the red. Government officials have been forced to look for cuts in government spending to satisfy creditors and the International Monetary Fund. Belaunde has come nowhere near his campaign promise of creating a million new jobs.

More than half of Peru's population remains unemployed or underemployed, according to government figures, even as inflation remains at a level of around 60 percent.

Meanwhile, the economic problems have all but frozen much of the ambitious program of building roads, housing and schools and colonizing of eastern jungle areas that comprises Belaunde's long-treasured vision of Peruvian development. And yet, the government has lowered trade tariffs, broken up land cooperatives, sold off state companies and dismantled many of the other statist innovations of 12 years of military rule.

"There is a frustration in the government because of the economic crisis," de Althaus said. "The government has established the general bases of its program, but it has not been able to . . . mount all of the necessary force."

The economic idling has sunk Belaunde's popularity rating from a high of near 50 percent early this year to a little more than 30 percent now, according to poll results published by the magazine Caretas. At the same time, the government's political problems have been sharply increased by the expanding activity of Peru's Andean-based Maoist guerrilla movement, the Sendero Luminoso.

After months of ineffectually tossing dynamite at government buildings and foreign embassies, the estimated 500 to 1,000 members of Sendero Luminoso, or Shining Path, suddenly emerged as a political issue earlier this year after they attacked a prison in the town of Ayacucho and freed 250 prisoners.

Now, weeks after another upsurge of Sendero activity provoked authorities to declare a state of emergency in Lima and three Andean provinces, opposition political leaders and even some of Belaunde's supporters have made a major issue out of the government's handling of the problem.

"He is looking very weak on the guerrilla problem," said Manuel d'Ornellas, a leading political columnist and strong supporter and friend of Belaunde. "It's a situation he hasn't wanted to recognize, and has played down too much."

While hard-liners have complained about Belaunde's refusal to order the Army to handle the guerrillas, other opponents and human rights groups have charged that mass arrests carried out under the state of emergency and abuses by police forces have smeared the government's democratic character.

For Belaunde, these charges have been both wounding and perplexing. A charismatic, personalist leader whose ideals were formed in studies as an architect and professor in the United States and campaign stumping here in the 1950s, the now 69-year-old leader indeed seems unwilling to accept that either guerrillas or human rights violations could exist under his government.

Belaunde, who lived in the Washington area during much of his exile, is to visit there Nov. 9 for a state dinner with President Reagan.

When asked in a recent interview about claims of police abuses, Belaunde responded, "People who talk human rights here -- they want to teach me?"

On the economic problems, Belaunde said, "The world is in worse shape now." But he argued that Peru had borne up under the effects of recession in industrialized nations better than most of its neighbors in Latin America.

Although Peru has indeed maintained a slightly positive growth rate this year while most economies in the region have remained stagnant or fallen off, Belaunde's sharp denials of problems in handling terrorism and his image of detachment from economic matters leads some analysts to say he has lost touch.

In a time of recession and insurgency, these critics say, Belaunde's large-scale visions of linking South American river systems, of outstripping poverty with rapid growth and his paternal, detached political style simply do not fit.

"When Belaunde was elected he was in a good position to carry the country forward," said Jose Matos Mar of the Institute of Peruvian Studies. "But he immediately looked backward, as if the situation was the same as before. His team is the same it was in 1963. The program has turned dated."

Other analysts say that the government is more accurately described as temporarily stalemated on the economic and terrorism problems.

Government officials say they must reorganize their programs and establish a clear, if more modest course.

Meanwhile, in the Andean region around Ayacucho, police and Sendero Luminoso guerrillas now seem stalemated.

For Belaunde, political analysts say, the danger is that a continuing impasse, with its publicized trickle of new violence, will result in mounting public calls for the Army to "reestablish order." The result could be a severe loss of prestige for the president, even the start of a chain of events that could lead to a coup.

For now, Peru's Army leadership is believed to be loyal to Belaunde and reluctant to be involved in a bloody anti-insurgent operation.