Iran's capital is a crippled city, an anemic but menacing relic of the boom town it used to be, now that demonstrations and clashes with troops have become a daily occurrence.

Thousands of people, mostly young men, roam the streets aimlessly. Thousands more wait in endless lines for scarce supplies of kerosene and bread. Few go to work because there is little work to be done and no way to get there. The city is closed as if for a holiday, but the atmosphere is not one of celebration.

Troops of the Iranian army, the only remaining instrument of the shah's authority, patrol the streets, one minute directing traffic, the next firing into the air and popping off teargas grenades. Young demonstrators taunt them with cries of "death to the shah," and scatter when the soldiers turn, in a cat-and-mouse game that constantly threatens to explode.

Most streets were quiet today, as large-scale demonstrations planned by opponents of the shah for another day of mourning failed to develop, but entire blocks were cut off by barricades and blazing tires and scattered shooting could be heard throughout the day.

Three young men were reported killed in one clash with the army and a disaster was averted when a molotav cocktail just missed a tanker truck full of gasoline on a downtown street.

The army sealed off the campus of Tehran University and mounted heavy guards outside the U.S. Embassy and the downtown headquarters of the National Iranian Oil Co.

The Marine guard on duty at the chained gate of the embassy was in full riot gear, complete with nightsticks and face visor. A strong tide of anti-Americanism is running through Iran, reflected in "Yankee go home" graffiti and assaults on American facilities.

In a few small ways, life went on more or less normally as the politicians negotiated over the future of the country . . . Young couples held hands in the parks, and tennis players turned out in the crisp sunshine. Most florists' shops and pharmacies were open as were some neighborhood grocery stores and big international hotels. Tehran's airport was open and baggage porters were working, but airliners flew without refueling, because the strike that has shut down the country's oil industry has wiped out fuel supplies.

Most public services have been canceled or curtailed. Garbage is piling up on street corners. Power cuts are frequent. Banks, business offices, the national airline, most shops and restaurants, the customs service, many government departments, the city bus system and all schools are closed. On top of that, the oil strike has brought a near-total lack of gasoline, cooking fuel and heating oil.

The result is that this as a city of 4.5 million people with little to do and no place to go. Many students are joining the antigovernment demonstration, but life for the majority is at a virtual standstill.

Only a few cars move where there were hundreds six month ago. Construction projects stand abandoned. Factories are shut for lack of materials and trucks are idle because the factories are closed.

Prices for what few goods are available are rising swiftly, but cash is scarce because the banks are closed. The 9 p.m. curfew has put an end to nightlife and many cinemas have been burned out anyway.

The state television continues to transmit, with the English service sending out American programs, Pink Panther cartoons, and bland news shows that gloss over what is happening here.

No one challenges the curfew. The young firebrands of the streets go home when night falls. But while they are out they appear to be reveling in the political license that has been bestowed on them by the power vacuum.

Knots of young men and women gather around leaflets containing messages from Ayatollah Ruhollah Khomeini, the shah's leading religious opponent - at least until the leaflets are ripped up by the soldiers.

Middle class Iranians, politically mute in the past, express themselves openly to total strangers, criticizing the shah, the Americans, or whomever they please. Crowds surround downtown kiosks selling unauthorized newspapers that fill the gap left by the disappearance of the press, first closed by the military government and now struck by journalists who refuse to work under military censoring.

One of the unauthorized papers printed today said it has a list of all the personalities contacted by Hossein Sadighi in his fruitless attempt to form a new civilian government earlier this week.

Another printed an open letter to Khomeini, who is in Paris, from the "people of Iran."

It said that "our schools are closed, our young people have nothing to do, there is no money in the country, the workers are all upset, nobody will accept any responsibility. There is no heating oil, stores are closed, our houses are cold."

The letter asks Khomeini to move swiftly to put an end to all this, calling him "our leader." What it does not say and what nobody seems to know, is how Khomeini or anyone else could build enough of a consensus to restore order here out of the mounting chaos.