Idle problems
 

The car 944 - 1984 has rest in the garage since october. At first I had an idel about 1200rpm but after I speeded up on the highway the idle did not go under 2800 rpm. My guess is problem / dirt in the flapperhousing so the flapper does not move easy.
Any comments?
regards Kent

More likely an air leak in your induction system.

Your 1984 Porsche 944 idling at 2800
RPM after storage likely points to a sticky airflow meter (AFM) flapper. Check the AFM for smooth flapper movement, inspect for vacuum leaks, ensure the throttle body isn't sticking, and verify the idle control valve (if equipped) and throttle position sensor are functioning properly.

Agree with above - stuck throttle valve not closing fully, vacuum leak are two possible culprits

Sticky throttle cable or pedal also possible.