A FEW YEARS AGO, the Federal Trade Commission was in trouble because it wasn't doing its job. It was a moribund agency that did little more than consume tax dollars. Now the commission is in trouble because it is doing its job too well. That's the meaning of a vote by which a House subcommittee has tentatively decided to cut off the money for many of the commission's current investigations.

This reversal in the way the FTC is regarded is a remarkable tribute to the aggressive leadership a series of chairmen have brought it. No one is suggesting any more, as was the case a few years back, that it be abolished for failing to enforce the antitrust laws protecting consumers against unfair practices in the marketplace. Now the complaint is that the FTC is enforcing these laws too strictly and driving big and small businesses wild with investigations into practices the staff believes may be deceptive or unfair.

The catalogue of the FTC's current sins is a long one, if you take the subcommittee's vote seriously. It voted to kill investigations in the operations of the oil and auto industries and the practices used by those who market, among other things, used cars, hearing aids, mobile homes, television advertising, home insulation, apparely, protein supplements, non-prescription drugs, and spa and funeral services.

Few observers are in sympathy with everything the FTC is doing these days. But the blunderbuss approach by the House subcommittee is ridiculous. If Congress thinks the FTC has established bad rules for the funeral industry, for example, it can pass a law eliminating or changing those rules. But this should happen only after hearings by committees concerned with the substance of the rules.

Deregulation of business has become popular on Capitol Hill in recent months and is now being pushed with a vengeance. Like the bill the Senate passed recently to expand the authority of the federal courts over the regulatory agencies, this attack on the FTC says more about Congress than it does about an agency's performance.