Lee Iacocca: What will this folk hero of American business do next?

The day is fast approaching when Chrysler chairman Lee A. Iacocca will be tested. Sure, he pulled off an incredible industrial miracle in restoring Chrysler Corporation to health when it was about to go under.

All this does, however, is raise such questions as: Just how good is this man Iacocca? What more could he do for the country?

Mr. Iacocca's rescue of Chrysler Corporation, accomplished partly by his negotiation of a $1.2 billion US loan guarantee, demonstrated an unusual ability to successfully deal with the government, the United Automobile Workers, the nation's banks, several state governments, Chrysler's salaried work force, thousands of auto suppliers, the nation's news media, and other groups.

Now labeled a folk hero of American business, he has been speaking to large groups of college students and union workers, receiving numerous ovations and revealing a potential for wide public appeal.

Surely, running a $15 billion company in today's worldwide auto market is challenge enough for most men. But many people around the country, and even Lee Iacocca himself, have a sneaking suspicion that he may have one or two more miracles ''in his back pocket.''

Iacocca has been visited or otherwise approached by politicians, businessmen, and others urging him to take on this or that new challenge. Frequently, he has been mentioned as a presidential candidate. This has made him consider which political party he might join.

''When I was poor, I was a Democrat,'' Iacocca says. ''Then I made some money and became a Republican.'' Ever a pragmatist, Iacocca says his recent struggle to save Chrysler has made him more favorably disposed toward the Democratic Party.

Right now, neither Iacocca nor anyone else knows when or even if he'll leave Chrysler. He has variously predicted that he would be leaving in two, seven, or 12 years. When this inconsistency was mentioned to him, he laughingly admitted, ''I don't know what I'm going to do.''

One thing that's certain is that he is prepared both personally and businesswise to leave the company and ''pursue other interests'' if he so elects.

First and foremost, Chrysler has completely repaid the $1.2 billion government-backed loan to the banks. This is a matter of great satisfaction and personal pride to Iacocca. Secondly, he has strengthened and organized Chrysler's top management so that the corporation can survive and prosper regardless of what he does himself.

The primary step in this regard was to set up an ''office of the chairman,'' vaguely described as an office for making major corporate decisions. In this group are Iacocca, vice-chairman Gerald Greenwald; Harold Sperlich, president of North American Automotive Operations; and Bennett E. Bidwell, recently lured from the presidency of Hertz Corporation to become Chrysler's executive vice-president of sales. Mr. Bidwell worked for Iacocca before Iacocca was fired by Henry Ford II as president of Ford Motor Company.

From the personal standpoint, Iacocca undoubtedly was a millionaire before coming to Chrysler five years ago. Since then he has made quite a few million more, largely because Chrysler's stock soared from $3 a share to $36, plus the fact that he had a large number of very profitable stock warrants.

A major question now is what would be the best job for Iacocca if he did decide to leave Chrysler. It's unlikely, however, that any corporate or congressional job would lure him from his present post.

One possibility is that, since he has repeatedly hammered at the nation's antiquated trade policies, he might be the right person to take over some new cabinet-level export post. There he might jawbone the nation's businessmen, workers, and Congress into embarking on an export program that could help reduce unemployment and further bolster the economy.

In a nutshell, Lee Iacocca has not yet reached his limit of competency or his point of failure. And actually, he has yet to make up his mind.