Greetings Candy,

You say it idles rough after the engine has warmed up? What is the RPM setting at while idling? Could be to low, tach should indicate around 750 to 850rpm. There could also be a problem with injection timing. Does is seem to blow black smoke while it sits there idling? You may have to put your hand at an angle to the tailpipe to realize it's doing this, not always visable just by looking at the exhausting gases puffing out the pipe. The next thing to check is engine temp while the car is at idle. Is it at 80 degrees C or close to it, or well below or above this temp? I've noticed that the engine on older 300 series diesels run better after warmed up because the thermostat has opened up and coolant pressure is no longer an issue in a somewhat back pressure coolant system. Post your observations and I'm sure we'll all try to get this figured out for you.

Charles

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"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan