PORT-AU-PRINCE, HAITI, NOV. 28 -- Haitians hope to vote Sunday in free direct elections for the first time in their history, in a test of their national will to bring stability to political chaos and break out of three decades of international isolation.

Also at stake is whether Haiti will finally banish the haunting political spirit of Francois (Papa Doc) Duvalier and his son, Jean-Claude (Baby Doc). They ruled this nation of 6.2 million like a feudal duchy for 29 years until the dynasty was ousted Feb. 7 of last year. A military-dominated three-man National Government Council led by Gen. Henri Namphy has been in power since.

While the vote is now set to go forward, some uncertainty still surrounds it even on the eve of the polls' opening nationwide at 6 a.m. Sunday. In a communique late today, the electoral council said it would delay the voting in five towns in the central Artibonite region. The council's headquarters in two of the towns, Gressier and La Chapelle, were burned by arsonists today, officials reported.

At least four new beating and shooting deaths were reported as armed bands hoping to block the elections battled with Haitians who want them to take place.

A band of about 15 former Duvalier paramilitary gunmen set up a roadblock across the main north-south highway between Port-au-Prince and Artibonite and blocked all traffic throughout the day, witnesses said. At least five groups of foreign journalists and a carload of American elections observers were threatened by the men there with pistols and machetes.

Regular Army troops stood by watching as the gunmen smashed a Canadian journalist's equipment. The gunmen also burned two electoral council trucks. One driver was missing.

Although only a quarter of all Haitians can read and write, the electoral council has been prevented by the government from running television and radio ads to explain the voting process.

More than 2.3 million Haitians, about three-quarters of the electorate, will choose among 22 candidates for president and hundreds for senators and deputies in the national legislature. There will be 6,000 polling places nationwide, with no more than 500 voters registered in each.

An official vote tally is expected by the end of the week.

The small neighborhood-based polling places, where most voters are likely to know one another, are seen as the most important check against fraud. With four presidential candidates leading the pack, a run-off between the top two is expected in late December, shortly after a round of municipal elections.

More than 200 international observers have flocked to Haiti. The large influx prompted Gen. Williams Regala, the other military officer on the government council, to warn the observers yesterday that "organizing the elections is strictly a national matter."

The presidential front-runners are Marc Bazin, a former World Bank official who served briefly as finance minister under Jean-Claude Duvalier; Sylvio Claude, a grass-roots Christian Democratic politician and long-time opponent of the Duvaliers; Gerard Gourgue, a human rights activist; and Louis Dejoie II, son of the man from whom Francois Duvalier stole a 1957 election to seize control of Haiti.

The ideological differences among the four men are slight.

"This is a campaign of personalities; one doesn't get the sense it's a debate of ideas," said one U.S. Embassy official. However, other candidates cover the full spectrum of Haiti's politics, including Dieveuill Joseph, a man who is presenting himself as a reincarnation of the Virgin Mary.

In this round Haitians "are more enthusiastic about their chance to vote than about candidates," observed Johnny McCalla, head of an elections monitoring team sponsored by the human rights group Americas Watch.

Two presidential candidates were murdered during the campaign. More than 500 Haitians have been hacked, shot or beaten to death in political feuding since the younger Duvalier fled to France.

In waves of vengeance killings, self-appointed posses hunted suspected Ton-Tons Macoutes, former members of the Duvalier paramilitary force, and any others they suspected of collaborating with the Duvalier family.

As the elections approached, hundreds of Ton-Tons Macoutes and former Duvalier allies struck back.

"The Duvalieristes are playing their last card," said electoral council treasurer Alain Rocourt.

When the Army intervened to restore order, it often killed more people. Otherwise, western diplomats said, Namphy's tenure has been marked by inaction that often verged on paralysis.

The government council "would have done better if it had provided some services to the Haitian people," a U.S. official said.

As a result, in a significant change during the transition, the Army became discredited for the first time in its modern history, the diplomats and other analysts said. When Namphy took over 22 months ago, a favorite popular slogan was, "Long live the Army!"

"The Army completely fumbled its task. Haitians are starting to hate them," said one European diplomat.

The decline of the 8,000-troop Army's popularity left Washington straddling a contradictory policy in the final months of the campaign. The Reagan administration strongly favored the elections, but opted to rely on Namphy's government council to guide Haiti toward them.

In recent months, the independent nine-man electoral council, chosen to organize the balloting under the terms of a constitution approved this year, emerged as a leadership force increasingly at odds with the government council.

Diplomats said that as the conflict grew, Namphy's council and his Army became less responsive to U.S. or other foreign views. The United States provided $103 million in economic aid but only $1.5 million in military aid to Haiti this year.

In an example of the U.S. dilemma, a Haitian Army captain, Antoine Atouriste, today grounded a U.S. helicopter flown in from Florida for the use of the electoral council as part of $8.1 million in U.S. elections aid.

Late yesterday, government council member Regala, who is also defense minister, for the first time committed the Army to provide security for the election. At dawn today Atouriste refused to allow the helicopter to fly, citing unspecified security grounds.

The electoral council has been pleading publicly for helicopters all week to deliver ballots to hamlets otherwise accessible only on muleback. In this particular dispute the U.S. Embassy came down on the side of the Army. A U.S. official said the electoral council had "lost interest" in the helicopters.

In a press release, the Foreign Affairs Ministry said today it had returned to Washington, unopened, an Oct. 14 letter from 46 U.S. legislators that criticized the armed forces for human rights violations. The ministry said only that the letter, addressed to Gen. Namphy, was deemed "undeliverable."

{Two congressmen who signed the letter and who were members of the official U.S. observer delegation, said Saturday they were informed at the last minute that the government council had barred them from Haiti. Del. Jaime B. Fuster (D-Puerto Rico) and Rep. Benjamin A. Gilman (D-N.Y.) called the Haitian decision "ill-conceived" and "arbitrary." Del. Walter Fauntroy (D-D.C.) had withdrawn earlier from the delegation following a dispute with former Duvalier allies.}

The Reagan administration is eager to see an elected government here because, U.S. officials say, Haiti is a time bomb ticking a few hundred miles from American shores that requires immediate attention to avert a social and economic catastrophe.

The average Haitian peasant earns only $150 a year on land ravaged by antiquated farming practices that cause more than 12,000 acres of precious hillside topsoil to wash away each year.

The hunger most rural Haitians live with drives thousands each year to risk the voyage in rickety fishing boats to the United States.