Just got this car..has high miles...260,132...but in great shape all highway miles..only problem is at idle..in drive or reverse it idles rough....really rough in reverse..whole car shakes...after its warm its not so bad in drive.still there..but still in reverse its still bad...runs great as long as its not at idle...also seems to idle low to me....previous owner had injectors cleaned and new plugs intstalled in the past few months...any ideas you guys can give me would be great..I'm a first time mercedes owner

 

1. Air filter clogged,
2. Vacuum leak at the throttle body, inlet manifold or associated hoses.
3. Worn, faulty or incorrectly-gapped spark plugs.
4. Uneven or low cylinder compressions.
5. Camshaft lobes worn.
6. Timing chain incorrectly fitted.
7. Blocked injector-fuel injection system faulty.

 

Hello idk if this would help anyone but i figured id ask here since chrysler own jeep and mercedes.

My 89 4.0 renix cherokee does that same thing with only 80 thou on it been doin this for a couple years and i havent been able to tackle it ive replaced a bunch of sensors .

Still tac bounces sometimes from 1000 to 900 rpm others right down to 400 rpm.

In reverse when i hit the pedal to fast it will die in park if i hit the gas too quick up to 2500 rpm and let off the pedal it will drop right down to like 100 rpm and almost die then come back.

Almost sounds like this problem your having

 

How can one confuse a cavilier with a jeep? That is so insulting That would be like calling an E class a reliant k car.

 

Steve,
Had the same problem, I replaced the Maxflow Sensor (about $50.00 on Ebay) it fixed my problem. You can do this repair yourself it's right on the top of the motor to the left.
Hope this helps you out.