Right-wing political killings, a stubborn Marxist insurgency and a faltering economy are troubling this country as it heads toward November elections to choose a civilian president to replace the current military government.

Both the far right and the far left appear to be using violence to try to provoke the Army's leadership into canceling the election in the name of the country's security, according to a variety of Guatemalan and foreign observers.

"We've noticed a tendency for violence to increase before elections," Lt. Col. Luis Rios, the Army's director of civilian affairs, said.

But even skeptics said the nation's top officers seem determined to hand over the presidency to one of the country's civilian politicians, for the first time since 1966. The Army, which has ruled Guatemala either directly or behind the scenes since a U.S.-backed coup in 1954, recognizes that a civilian president would find it easier to obtain increased U.S. aid, and the officers are tired of trying to cope with accelerating inflation and stagnant growth, Guatemalan officials and foreign diplomats said.

In addition, the armed forces will continue to exert considerable influence even after Gen. Oscar Mejia Victores steps down as chief of state, Guatemalan politicians and foreign diplomats said. The new president will govern with the knowledge that offending the Army could lead to a military coup, of which there have been two here in the past 3 1/2 years.

"I do not think you can expect a total, 180-degree shift in which the Army says it will be totally out. That would be wishful thinking, utopian," a senior, non-Latin diplomat said here. He added, however, that inauguration of a civilian president would be "a tremendous step forward."

Opinion polls and political pundits agree that Christian Democrat Vinicio Cerezo is the early front-runner. He proposes a cautious program of economic and political reforms.

Cerezo, viewed as the least conservative of the leading candidates, is said to be the one who most worries the Army. The military is believed to look with greater favor on Jorge Carpio, a conservative newspaper publisher, and on longtime rightist leader Mario Sandoval Alarcon.

Whoever wins the Nov. 3 ballot -- or the runoff that ensues if no candidate wins a majority -- will take office in January facing a host of problems.

High on the list is the so-called dirty war of assassinations and kidnapings of left-leaning political activists and other suspected supporters of guerrillas fighting the government. Human rights activists and church sources said killings and abductions in the capital and in at least one rural area west of here have increased in recent months, and they blamed the government's security forces.

"Before handing over power, they want to sweep things up a little," Nineth de Garcia, a leader of the Mutual Support Group, said. Her organization, founded a year ago, has become Guatemala's leading human rights organization and two of its leaders were assassinated in late March and early April.

Other victims in the city this year have included about 10 professors and student leaders at state-financed San Carlos University, three Guatemalan social workers employed by the U.S. government-backed Inter-American Foundation and several union leaders, according to the Mutual Support Group and church and university sources. Armed men in civilian clothes staged most of the killings or kidnapings, they said.

Chief of state Mejia denied at a news conference that the armed forces were responsible for any of the killings. He said the Mutual Support Group was "manipulated" by the guerrillas, and attributed the violence at the university to infighting among drug traffickers.

"It appears that there is terrorism in all of the world. We can't be exempt from these problems in Guatemala," Mejia said at the news conference last week.

Statistics compiled by the U.S. Embassy on political violence nationwide showed that killings and abductions were continuing this year but had declined somewhat from last year. The Mutual Support Group and church sources suggested that the U.S. figures were incomplete but did not offer alternative figures.

To some extent the vigilante squads probably have responded to an increase in leftist-oriented political activism this year, according to a variety of sources. Student associations that describe themselves as progressive have stepped up organizing since late 1984, student leaders said. The Mutual Support Group, which says it has 700 members, drew attention with a series of marches.

This modest surge of political activity was accompanied by an increase in guerrilla attacks in the countryside at the start of the year. The Marxist insurgents, estimated by the Army to number about 2,000, remain active despite having lost considerable ground to the government since 1981 and 1982.

Increased guerrilla probing has triggered a tough reaction against peasants suspected of helping the rebels in the area around Patzun, 30 miles west of the capital, according to diplomats and other sources familiar with the area. The U.S. Embassy said that 21 persons had been killed and 34 abducted this year in that municipality, the equivalent of a county, and a diplomat said that government security forces there had "overreacted."

While violence has attracted most attention, the economy is the principal worry of most Guatemalans. The officially recognized inflation rate has quadrupled this year to 16 percent from 3.8 percent in 1984, and diplomats said that a more realistic figure is 60 percent. The economic growth rate was expected to stay flat again this year after a minimal expansion of 0.2 percent last year.

The nation's powerful business community blocked a government attempt in April to push through austerity measures including a 50 percent tax on luxury imports. Diplomats and university economists accused the nation's upper class of sabotaging the economy by refusing to accept new taxes.

"The private sector here does not seem to want to assume any kind of responsibility for development of infrastructure or for the well-being of the populace as a whole," a diplomat said.