Third World history abounds with governments overthrown for economic neglect and mismanagement, but only that of Sudan has survived with difficulties so vast that one observer remarked, "How do you kill a corpse?"

Early this month, however, traditional Sudanese passivity, long cited to explain the popular acceptance of privation and suffering, gave way to angry street demonstrations.

Young Sudanese burned tires in the streets of the capital to protest gasoline and bread shortages, the most obvious and ominous hallmarks of the "economics of mafi," Arabic for, "There is none."

President Jaafar Nimeri's reaction was to close down schools to save fuel -- and prevent the young from congregating and staging further demonstrations.

Whether the protests even jolted the government, run by Nimeri under a personal system without regular Cabinet meetings or set institutions, remains open to question. One ranking Sudanese official even says that "no one knows" how decisions are made.

American and other western officials are distraught over the absence of government policy. One banker voiced the frustration of many when he said, "Apparently Nimeri feels people spend so much time finding enough to eat that they don't worry about the rest."

"The gas tank needle is on empty," an observer remarked. "But the country just keeps going on the fumes."

Such is the plight of Africa's largest state, a potentially rich country that in the heady days of the strong petrodollar was going to transform itself into the Arab world's breadbasket -- thanks to oil money, western know-how and Sudanese labor.

Confronted with famine, a major and open-ended refugee influx from neighboring countries, civil war and the self-inflicted economic disruption caused by radical Islamization of the banking and tax systems, the regime is facing its greatest challenge since Nimeri seized power in 1969.

Whatever his own inner doubts, Nimeri in public projects seamless confidence. "He is like a piece of military equipment," a diplomat said, "rudimentary, simple, not easily clogged and suited for continuous operations with a minimum of maintenance."

"He is not popular, attractive, liberal or by any means a sound economic manager," he added. "He's a bare-knuckles fighter, full of vigor and an urge for power singularly lacking in his opposition."

Nimeri of late also has demonstrated that he can resort to repression to intimidate, although he is scarcely in the same league as presidents Hafez Assad of Syria or Saddam Hussein of Iraq.

The economy is his Achilles' heel, and that of his despairing American allies who provide Sudan with the biggest aid program in black Africa. They are well aware that Sudanese public opinion has tied the United States closer to the president's person than Washington likes.

Symptomatic of the U.S. dilemma is whether to release $87 million earmarked for purchase of desperately needed gasoline and other petroleum products.

Current guidelines require that Sudan must first put up $30 million of its own -- money it simply does not have. Hard-liners argue the government also must stop Nimeri's cronies from concluding questionable middleman deals that have led to the nicknaming of one of the president's associates as "Mr. 25 Percent."

Policy pragmatists insist the oil shortage causes a ripple effect, magnifying the serious existing shortages by reducing road traffic and increasing the deadly effects of famine. They want the United States, the International Monetary Fund, the World Bank and other major aid donors to suspend their tough conditions for emergency relief and other humanitarian aid.

Denying Sudan petroleum products only serves to undercut the leading U.S. role in providing $300 million in emergency western food aid to 5 million Sudanese as well as refugees pouring in from neighboring Ethiopia.

Within the disorganized Sudanese opposition similar arguments rage. Only in blaming the United States for providing the aid to keep Nimeri in power do they agree.

Doctrinaire members of the banned Communist Party favor cutting all U.S. aid even at the certain risk of causing more deaths from starvation.

More moderate opposition voices criticize Washington for allegedly playing favorites and easing the IMF's rigorous demands for basic reform. Others argue just the opposite, insisting that the United States is trying to starve the Sudanese into submission to Nimeri.

Amid such mutually contradictory charges, Sudan's economic problems fester.

The classic economic indicators illustrate that Africa's biggest country also has its biggest headaches. Foreign debt is approaching $9 billion, roughly equal to annual gross domestic product.

The balance of payments deficit is more than $800 million. Sudan is $110 million in arrears to the IMF, which has cut off arduously negotiated standby credits.

The treasury is so short of foreign exchange that most trade is by barter -- and on onerous terms.

The main refinery at Port Sudan shut down five times last year for lack of crude oil, and tankers routinely anchor offshore until the government scrapes together the necessary hard currency. Resulting refinery start-up costs are enormous.

The only international obligation Sudan has met for months -- and then often with considerable delays -- is the payment of $30 million representing the much reduced rescheduled reimbursement of commercial loans. Without those payments, all foreign exchange would dry up.

The Sudanese pound, officially devalued to $2.10 only last October for the most used of its five exchange rates, is now worth less than half that much.

With lines outside money changers even longer than those outside bakeries and gas stations, Sudanese are determined to get their funds out of their own currency.

Two weeks ago specialists predicted a 5-pound dollar by Easter. But so fast was its depreciation that by the end of last week the dollar already was quoted at 4.8 pounds.

Such massive capital flight, complicated by a drastic drop in remittances from Sudanese working overseas, only underlines the lack of business confidence.

Bankers and economists put the blame not on crop failure and traditional mismanagement by Sudan's "chief noneconomist," as one man called Nimeri, but on the confusion caused by the Islamization of the economy since 1983.

Carried out by three Islamic fundamentalist mullahs who have become Nimeri's chief palace advisers -- and Moslem law professors from Omdurman University -- these changes caused so much bewilderment that Finance Ministry officials called up diplomats in the hope that they understood what the loosely worded legislation meant.

Originally swept away in favor of zakat, a 2.5 percent flat rate tax on practically everything, were personal income taxes, corporate profits and rent, development and production taxes.

But when zakat failed to produce the revenues the mullahs predicted, the old taxes came back, albeit with changed names.

The legality of interest charges remains very much in doubt. The radical banking law now basically forces banks and clients to enter into partnerships. The stress is on quick profits, and economists say that is responsible for the hoarding of sorghum and wheat, which have quintupled in price as a result.

Mohamed Faisal Abdul Aziz, the Saudi prince who runs the Islamic bank bearing his name here, is being allowed to pioneer this radical version of Islamic banking which remains anathema in Saudi Arabia itself.

Further angering even upper middle class Sudanese -- who, like the poor, must line up for bread and other necessities -- is the knowledge that Nimeri's favorites escape the rigor of the Islamic penal code, which punishes theft with amputation.

One Nimeri crony who owes about 120 million Sudanese pounds to several government banks is not in jail because misuse of public funds does not constitute theft as defined by the Islamic penal code.

On the brighter side, the few remaining optimists point out that production of cotton -- the main export earner -- has doubled thanks to increased farmer incentives.

And no matter how depressing the mess is now, any Sudanese taking over after Nimeri is thought unlikely to repeat the regime's Soviet-style nationalization of the early 1970s, a policy that hamstrung the economy for a decade.

"There hasn't been a coup here in a long time by Mideast standards," a foreign analyst noted. "But just because people think this mess cannot go on forever doesn't mean it will happen anytime soon."