LIBERIA

Sandwiched between swamps and the sea and saddled with a hot muggy climate, Monrovia, like many other West African coastal capitals, is a difficult place to live.

But Liberians say their country's political climate at least has improved. Harassment by unruly armed soldiers and confiscation of money, cars, and houses have stopped. Soldiers are back in the barracks, property has been restored, and compensation paid for looting.

The violent coup of 1980 mounted by a group of young African officers who toppled the ruling elite - descendants of freed American slaves who sailed to Africa before the American civil war - profoundly changed the power structure. Out went the tiny minority that ruled Liberia since 1847, and in came the more poorly educated, indigenous majority.

Initially there were considerable confusion and insecurity as the new regime headed by Master Sgt. Samuel Doe consolidated itself. But three years later, after a string of attempted coups, Doe appears to be comfortably established. The President has swapped his camouflage battle dress and hand grenades for smart three-piece business suits, and he has taken a strong interest in pan-African politics.

Relations with Washington did not falter when Doe drove the Americo-Liberian descendants out of power. In fact, ties with the United States have grown stronger. Doe's young, inexperienced administration sought - and got - significant new US aid and technical assistance.

Talk in the capital these days is not of plots and purges but of a new constitution and the proposed return to civilian rule in 1985. Doe recently approved a draft constitution prepared by an independent 25-man commission. The constitution would limit the power of the presidency and promote a multiparty system. It would encourage national rather than tribal parties by requiring that a party have support in at least six of the nation's nine counties.

The proposed constitution will be examined by a national assembly later this year and then put to a national referendum.

President Doe has said that he and other members of the People's Redemption Council will withdraw from government, but not everyone is convinced. Presidential aspirants have been hesitant to declare their candidacies early, possibly feeling it safer to keep a low profile until the new constitution has been officially adopted and an election date set.

Some here worry that if the economic situation continues to deteriorate, social unrest could provide an excuse to delay the elections. Mr. Doe inherited a bankrupt economy, due partly to extravagant spending by his predecessor, William Tolbert. But Doe has been unable to prevent the situation from deteriorating further.

The government had decided to quadruple military salaries and double civil service salaries - a move that was politically popular because it would tend to lessen corruption, which is endemic here. But the salary hikes proved financially catastrophic, and Doe was obliged to announce pay cuts in December of up to 25 percent.

Doe has taken other actions to show he is tough on corruption. During a severe stage of the oil shortage, he went to a local refinery in Monrovia and personally arrested officials for stealing petroleum. But the leader has rebuked some others, including his foreign minister, for criticizing the high living of government officials.

Depressed world steel, rubber, and timber markets have badly affected Liberian export earnings and a traditional trade surplus has been dipping toward a deficit. The coup also frightened a lot of investors who took their dollars out of the country. But US investors like Uniroyal, Firestone, and Bethlehem Steel are still here. The level of US investment is about $500 million.

Some expect the economy to pick up again in the late '80s as iron ore, natural rubber, and timber prices recover. Development of hydroelectric resources and offshore oil exploration by AMOCO could make the country self-sufficient in energy. Diamonds, gold, cocoa, and coffee are also sources of potential wealth.

Since the coup, the country has been kept afloat mainly by the International Monetary Fund and US aid. A one-year IMF standby agreement negotiated last year gives the country $60 million. In return for this aid, the IMF is requiring the government to cut its operating expenses by 15 percent and also limit its borrowing and honor debt commitments.

US aid has risen to $72 million in fiscal 1983 from $8 million in 1979, one of the highest levels of aid of per capita in sub-Saharan Africa. US interest in Liberia stems from the Reagan administration's desire to assist a ''friendly'' country toward economic stabilization, particularly one headed toward civilian rule.

Much of the US aid is being used to service the country's external debt. Relatively little funds are available for development projects.

The government is so short of cash and creditworthiness is so low that it cannot finance energy imports. Earlier this year there were serious shortages. Air conditioners and refrigerators stopped working. Lights went out and long gasoline lines formed.

The crisis, accompanied by allegations of corruption and mismanagement at the local refinery, eroded the government's dwindling stock of popularity. ''But the people still have plenty of rice to eat and that is what really counts,'' an observer commented.