PORT-AU-PRINCE, HAITI -- At morning rush hour recently, a gruesome roadblock was set up on Boulevard Harry Truman, a main thoroughfare that runs along the fetid seaside here.

The obstruction consisted mainly of a dead man in the middle of the road. Extending in a line from his bony corpse to the road's shoulders were rusted car parts, tree branches, old tires and rusted tin cans. At 8:30 a.m., traffic came to a halt.

The man had died two or three days earlier, but no one would come for his body, according to local residents, hundreds of whom thronged at the site of the roadblock, jostling and shouting. Frustrated by the authorities' nonchalance, they said, a few men dragged the man's body into the road, made it the centerpiece of the roadblock, unbuttoned his pants to expose his genitals, and scrawled in French on a placard nearby: "This is how people die in Haiti -- like a dog."

The event underscored the rage that erupts every so often in Haiti, the Western Hemisphere's poorest nation, where fear and distrust seem to color the attitude of ordinary people toward nearly every important public institution.

Less than two years after jubilant crowds filled the streets of this seamy capital of 1 million to celebrate the hasty departure of president-for-life Jean-Claude Duvalier, Haitians are in a mean mood.

Resentful at what they see as the snail's pace of social and economic change, pessimistic about the chances for fair presidential elections in November and scornful of the chaotic proliferation of political parties and candidates, more and more Haitians are beginning to doubt whether the promise of liberation at the close of 29 years of Duvalier family dictatorship will ever be fulfilled.

Some respected Haitian leaders said that with the notable exception of the press, which has been unfettered, there has been little fundamental domestic change since "Baby Doc" left Haiti Feb. 7, 1986, bound for France. Some hinted that more violence may be in the offing.

"The basic change that had to come didn't come," said the Rev. Hugo Trieste, the left-leaning, anti-American director of Radio Soleil, Haiti's most popular radio station and the principal source of news for the nation. "People were made to believe that they achieved victory when Duvalier left, and this is false."

Said one diplomat: "The Duvalier overthrow was almost like a surgical strike. There was no wider social revolution. Everyone thought they'd suddenly all have jobs and be driving cars, but {Duvalier's departure} didn't change the basic reality of poverty."

Local elections, originally scheduled for early summer, have fallen by the wayside for the time being, a casualty of the political turmoil that boiled over in late June. That was when the military-led, caretaker government of Lt. Gen. Henri Namphy briefly tried to seize control of the fall presidential elections before its mind was changed by violent street demonstrations and general strikes.

Haitians have become jaded by decades of political leaders who have refused to yield power voluntarily. The government's attempt to grab control of the elections from an independent electoral council left many convinced that Namphy and his powerful No. 2 man, Brig. Gen. Williams Regala, have no intention of leaving office either.

Neither Namphy nor Regala has consented to an interview in recent months, but government spokesmen last week reiterated Namphy's longstanding commitment to step down next February when an elected civilian government is scheduled to assume power.

In addition to the lack of public backing for the government, other public institutions also are seen as teetering on flimsy support.The Catholic Church, instrumental in the maneuvering that brought about Duvalier's ouster, fell silent after he left and failed to offer guidance or a new social agenda for the post-Duvalier period, according to Haitian and foreign sources.

Lately, the church has suffered further in public esteem as a result of a high-profile rift between so-called "liberation theologians," led by the outspoken, charismatic Rev. Jean Bertrand Aristide, and the National Conference of Bishops. Church leaders have watched with growing discomfort as Aristide's public statements, especially those calling for the ouster of the interim government, have turned more strident. A confrontation between Aristide and the church leadership last month resulted in the bishops backing down.The Army, which once helped to maintain the Duvaliers in power, is now identified with the unpopular military government, as well as with the seemingly random violence that marked recent demonstrations. Troops were blamed for killing at least 37 civilians. Several Haitian and foreign journalists reported that soldiers had fired upon them.Political parties, most of which have sprung up since Duvalier left, are splintered and based largely on the personalities who lead them. For a time this summer a large number of them seemed to coalesce into an organization calling itself the Group of 57, but it did not have any significant impact, according to diplomats and Haitian politicians.

Even some of the candidates regarded as centrists show few signs of being willing to unite, despite the behind-the-scenes urging of U.S. diplomats. The elections are set for Nov. 29, but there is some doubt that they will take place as scheduled.

There also is a looming question of whether all the candidates -- there are several dozen at this stage -- will be able to get the necessary permission to run. Under the provisions of the new constitution, each candidate must prove he is free of taint from association with the Duvaliers. If he served under the Duvaliers, a candidate must produce a seal of approval from the government's Public Accountant showing that he did not misappropriate any public funds while in office.

That requirement may be an obstacle to several candidates, including respected leaders such as Marc L. Bazin, a former World Bank economist dubbed "Mr. Clean" for his five months of corruption-bashing as finance minister for Jean-Claude Duvalier. No one is quite sure, if only because no one has witnessed a clean election in Haiti in more than a generation.

"The general attitude of the population is not in favor of the candidates," said Dr. Louis Roy, who helped draft the new constitution, which was approved by voters in March. "After 30 years of the Duvaliers, all institutions, to survive, had to bow to the regime: judges, the Army, everyone. Now no one knows how to proceed, and the result is there's not much confidence in these institutions."