1992 904GL Rough Idle, Shifting Surges

[JohannReinhard]

Hi all,

Having a spot of trouble with my RWD Brick. When the car is started (no hot starts, slow starts, stalling, etc) the engine will idle slightly rough (swings of roughly 100-150 RPM). The worrisome part is when I shift from park to drive, or reverse. The engine will idle very rough, and the RPM swings double. It smooths out after several seconds, and the car remains perfectly drivable.

I have had the throttle body checked (will probably do it again, I didn't quite trust that shop), but not the IAC. I'm worried, because I like my 940 and want it to keep going. Any thoughts or suggestions? I can't imagine why shifting would cause such a drastic change in the idle.