Hello all,

I have a 1983 300SD which runs excellent when it's cold. It starts right up, idles smoothly, accelerates fine..........runs and drives like it should! However, after driving around for a bit and when the car really warms up.........it idles very rough. It idles so rough that it sounds and reminds me of an old Model T ford! It shakes the whole car when you're at a stoplight with your foot on the brake. However, when you accelerate from the light, it smooths out immediately and runs/drives fine. The problem is only at idle. It doesn't matter if the tranmission is in gear or not, and it doesn't matter if your foot is on the brake or not.......it still idles rough. It feels like a cylinder might is missing or similar since the rough idle is very syncronized/timed (ie: 1...2...1...2...1...etc.) and is not an erratic rough running. I've checked the vacuum lines for a leak and all appear to be okay.

Any ideas and/or tips? Has anyone had a similar problem? Any help would be greatly appreciated!

Thanks, Al.