Kohl maintains the balance against Strauss - and the Soviets

West German Chancellor Helmut Kohl is once again confounding his critics. Just as complaints were mounting about a listless drift in leadership, Dr. Kohl has again shown who's boss - even producing a bit of good domestic and foreign news.

It won't quash the grumbling: The gadfly magazine Der Spiegel maintains that Kohl ''has no concept in economic, social, or security policies.'' The liberal Die Zeit faults him for being better at ''the instinct for power'' than at ''designs for society.''

But Kohl's latest moves should at least quiet this wave of discontent.

Kohl's unusual public assertion of his authority came in response to the latest challenge from Franz Josef Strauss, Bavarian premier and leader of the junior conservative party, the Christian Social Union. In mid-November Strauss again advanced his claims to a major Cabinet post in Bonn. The target was clear; he wanted to replace Free Democratic Economics Minister Otto Lambsdorff.

Indictments are to be made next week in the long-simmering FLICK scandal about illegal industrial contributions to political parties. The rumor mill has it that Mr. Lambsdorff is likely to be one of the officials indicted.

In response to Strauss's probing, Kohl announced that Lambsdorff would stay on in the Cabinet. Unproved indictments would not be cause for resignation, he indicated; no moves would be made prior to the initial findings of judges in the case - an event that won't happen for some time.

This defense of Lambsdorff is part of Christian Democrat Kohl's careful balancing act in his coalition of the Christian Democratic Union, Christian Social Union, and Free Democratic Party.

Ever since the election last March, Strauss has been intent on sweeping the Free Democrats aside and leaving a Christian Democratic-Christian Social Union government in which Strauss might become dominant. And ever since the election Kohl has been equally intent on keeping the Free Democrats in place as a foil to Strauss's ambitions. Although the Free Democrats got only 7 percent of the vote, they gave Kohl his majority.

While Kohl has been reasserting his own leadership vis-a-vis Strauss, he has also been rallying some support by pointing to a pickup in the economy and a successful holding operation in Ostpolitik.

The just-announced projection of 2.5 percent real growth for 1984 is modest and well below the current surge of the US economy. But it is considerably better than this year's projected 1 percent or the actual decline of the past two years. And it means the beginning indicators of recovery have not yet sagged , as it was feared they would.

Kohl's greatest success, perhaps, is evident in the conspicuous preservation of friendly relations with East Germany and the Soviet Union even as new NATO missiles arrive in Europe, including West Germany.

Lambsdorff has just come back from talks in Moscow saying the Kremlin will not disrupt bilateral economic relations as retaliation for the missiles. And East and West Germany have just signed a new postal agreement that will significantly expand direct telephone dialing and telex links between the two states.

Bonn is paying for the expansion - with a doubling of its annual payment to East Berlin through 1990 to 200 million marks ($80 million). But for Bonn the increase in contacts between East and West German citizens is worth the cost, especially when it locks East Berlin into not making too big a fuss about the missiles.