Engine idle rough when stopped at stop light/sign and still in "Drive", when accelerating it smooths out to normal but stopped and <5mph it runs extremely rough. Engine was just rebuilt, are there any adjustments I missed to help smooth out this rough idle problem. Any suggestions/tips would be greatly appreciated. Thanks, Rick.

Car - 1993 190E 2.3

First thing I would look for is the engine mounts. If the engine is rebuilt, are the engine mounts new, and/or properly tightened?

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Originally posted by Zoonhollis:
First thing I would look for is the engine mounts. If the engine is rebuilt, are the engine mounts new, and/or properly tightened?

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Clarifying; by rebuilt I mean top end, valve job, head gasket replaced. Engine mounts are good and rough idle was not present prior to top end rebuild.

Had a problem like that on my car. It was attribute to dirty gas...Perhaps dump some injector cleaner in there! Good Luck

Try to isolate whether it is an ignition problem or fuel problem. Are the spark wires relatively new. If they are the originals, the metal connectors can go bad and give a rough idle but the ignition will provide enough spark to go through them at higher rpm. You could pull a plug and see if you can tell which one is discolored. Sometimes you get a bad one or it gets a cracked insulator on installation. If one is darker than the others replace it and see if that corrects the problem. If not check the spark wires with an ohm meter. You should have continuity with resistance of about 2K ohms or less.