Prime Minister Takeo Fukuda's Cabinet reshuffle represents a recent conviction on his part that he must show a new economic face to the world and take a bolder, more decisive role in reviving Japan's economy.

By moving several new men to the center of action today, he acknowledged that his 11-month old go-slow formula was not working. It was an admission that many of his critics have been right in saying for the past few months that he had not succeeded in the role for which he was chosen, managing a strong economic recovery.

The changes seemed to observers here as particularly designed to soothe relations with the United States. Two of the most important new economic officials are highly regarded by U.S. representatives and a third is best known for espousing an economic offensive along the lines insistently urged by the United States in the current trade talks.

In a speech to his new Cabinet tonight, Fukuda said that U.S. Japan trade problems are "the most urgent" of several severe economic issues facing the country.

From the American point of view, the appointment of Nobuhiko Ushita as a kind of foreign economic minister without portfolio was especially welcome. Ushiba will be in charge of Japan's worldwide trade problems and will act as a roving emissary and negotiator. He is likely to be the man to handle the delicate negotiations if and when Robert Strauss, the special U.S. trade representative, comes to Tokyo for a round of crucial talks scheduled for next month.

Ushiba was ambassador to the United States from 1970 to 1973 and is known as an otspoken authority on economics and world trade as well as savvy negotiator.

A second major change was the appointment of Kiichi Miyazawa, 57, as director general of the Economic Planning Agency and as chairman of a Cabinet committee overseeing several economic and trade ministries. A sophisticated veteran in economic affairs, he has been described as "the foreigner's Japanese" because of his excellent English and internationalist views. A member of the Parliament's upper house, he has been both foreign minister and misister of international trade and industry in previous Cabinets.

Probably the most painful appointment Fukuda had to make was that of Toshio Komoto as head of the Ministry of International Trade and Industry, which has broad authority over domestic economy, including both imports and exports.

Komoto is a leading proponent of government measures to expand Japan's domestic economy and,as such, ha d differed publicly many tomes with the caustious paths chosen by the prime minister. He has repeatedly called for lower banks discount rates and greater government pumppriming to build up domestic demand. Most recently, he espoused a S3 billion program of emergency imports - mostly oil and uranium - to help reduce Japan's embarrassingly large trade surplus. It is a move that Fukuda has never quite been willing to embrace entirely.

The choice is especially pleasing to the United States, which has been preaching the virtues of economic stimulation to Fukuda's government for months. The United States hopes that an expanding Japanese economy will buy more of the manufactured goods from America, Europe and some developing countries and thus become truly one of the "locomotives" that will help pull the world out of a recession

It was the complaint at home and abroad that Japan was making too slow a recovery that caused Fukuda to make today's changes.The criticism has been growing all year, and in recent months it was echoed by the Japanese business establishment, which has great influence in Fukuda's Liberal Democratic Party.

Big business was particularly disturbed that Fukuda seemed unable to do anything to stop the Japanese frpm its rapid appreciation in relation to other currencies. The rising yen had made Japanese exports so expensive that many companies are losing their world markets. Stocks of several prominent exporting companies have fallen sharply in recent weeks.

In his other appointments, Fukuda showed a tendency to stick with loyal and trusted friends. He shifted his chief Cabinet secretary, Sunao Sondoda, to the post of foreign minister, a movie likely to enchance completion of a JapanChina peace treaty that Sonoda has long championed. Another Fukuda friend, Shintaro Abe, was moved to Sonoda's old job.