Although there was relief, even joy, ere at the demise of the brutal and corrupt four-year rule of ousted president Romeo Lucas Garcia, there is widespread discontent with the junta that replaced him and great uncertainty about its stability and longevity.

Only two weeks after being propelled to power in a coup by young military officers, the new triumvirate led by Gen. Efrain Rios Montt is surrounded by public whispers of new plots, and new political maneuvers have become so commonplace that they do not even make the front pages of Guatemalan newspapers any more.

"This thing is fragile, very fragile," noted one senior diplomat here in the Guatemalan capital. "It is still much too early to predict just how things are going to work out."

There are many signs of the junta's uncertain hold on power, such as refusals by military units in the field to accept new commanders and the failure to jail and put on trial high-ranking officials of the ousted government whom the new junta had dismissed for alleged abuses.

"There is grumbling at almost every level of society and that is what keeps raising the prospects of coups d'etat," noted a diplomat. "No one is completely happy with the junta and that could be dangerous given the wide divergence of forces around the presidential palace."

At the root of the general uncertainty lies confusion about just where power lies these days in Guatemala, the Central American country with the largest population and strongest economy.

The March 23 coup, planned by captains, lieutenants and majors, indicated that military power at least, lay with the officers who commanded the troops, not with the generals who for so long were involved in the abuses of power of the military-dominated governments that have ruled Guatemala for almost 30 years.

But the sudden emergence of a junta of two generals and a senior colonel immediately after Lucas Garcia's bloodless overthrow indicates that the military high command has moved to take political control of the movement and reimpose the authority of senior officers.

Aside from the mutual goal of getting rid of Lucas Garcia and his cronies following last month's election, which was marred by widespread accusations of fraud, the aims of the young officers and their senior commanders seem to have had some noticeable differences.

The young officers' movement wanted quick and drastic changes--a purge of corrupt officers and policemen, quick new democratic elections in which no military men would be allowed to take part, and an immediate change of Guatemala's tarnished image so it could become eligible for the U.S. economic and military aid, which was cut in 1977 because of human rights abuses and which they consider necessary to confront the leftist guerrilla insurgency in the countryside.

The senior officers, while wanting Lucas Garcia's crowd out, have been opposed to any breakdown of the military's order of succession and command and have sought to restrict any punitive actions taken against the ousted members of their military class, seeking to avoid a dangerous precedent that could, some say in private, rebound against them should the political tables turn yet again.

In between these two forces, and part of both, is the personality of Rios Montt, a former director of the military academy, a one-time presidential candidate whose victory was taken away from him in 1974 by his military peers, and, for the past 3 1/2 years, a born-again Christian evangelist who has devoted himself to preaching and teaching Bible school.

Saddled with two senior military officers in his junta, Rios Montt also has the leading young coup makers as "advisers" in his presidential office.

Rios Montt's position has become even more precarious because of the emotional, personal style of his leadership, which features public pleas for the guidance of God in steering Guatemalan affairs. His highly charged television statements call for everyone in the government and country to undergo a spiritual and moral reform to allow the reformist policies, which he says can cut the ground from under the guerrillas.

"We must repent. We have to change our morality," Rios Montt said at a special gathering of senior civil servants this week. "All that was stolen, all that we here stole, we must give back to the country in another way. Sirs, either we get it together or we will all be led away by the guerrillas as prisoners."

As if Rios Montt did not have enough problems trying to steer a course between the young officers who brought him to power and his senior colleagues with whom he must share it, his rule is being increasingly questioned by rightist politicians whom he has frozen out of his circle, as well as the still grumbling supporters of Lucas Garcia's government.

Appointments of new commanders have on at least three occasions been resisted by units in the field, forcing Rios Montt's junta to negotiate rather than command.

And despite a general crackdown on the secret police and corrupt civilian officials in the Lucas Garcia government, no formal charges have been placed against any military man in the previous government.

Relieved of their posts, the ousted generals have been confined to their residences and forbidden to leave the country. None, however, is under actual arrest, and some have been moving around Guatemala, heightening rumors and reports that there are new coup-making plans in progress.