83 300D turbo 230k miles
It just started doing this yesterday, with no known cause.

Very rough idle.
In all gears.
Reverse is much much worse than the others. Violent. Scary.
Problem goes away when throttle applied. (runs normal / "smooth")

Oil level and pressure good. RPMs normal.
The only thing that was done before this started happening was that I pressed on the "gas" pedal a few times with the car/engine/key off.

Help please...

--Ed

What do you mean by "rough idle?" Is it helluva lot of vibration like engine and tranny mounts collapsed. Or is it stumbling and hunting like vacuum leak or injector/fuel flow problem.

Vibration, lots of it.
I know the engine mounts are shot, but it behaves fine when revving or driving.
The fact that is is MUCH worse when stopped in R has me lost.