Help!! My 87 300E idles extremely rough after sitting still in traffic for an extended period of time. The car vibrated badly, and the engine felt like it was going to cut out (although it never did). The idle speed, however, remained pretty much at 1,200 rpm. When I applied gas when the traffic began to move, the engine acted like not all cyclinders were firing, and there was not much power to get up to speed. I can hear knocking from the engine if I applied too much gas. But as soon as it got back to crusing speed, the power band retuned and the vibration ceased.

What would be the cause? It happened frequently when I got stuck in traffic. I am afraid one of these days the car will just quit and I will be the cause of a major traffic jam in the Washington beltway.

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95 R129
04 Infiniti G35.5 BS
10 X204

Went to search engine and keyed in "300E idle". Came up with this:

http://www.peachparts.com/shopforum/search.php?action=showresults&searchid=378566&sortby=lastpost&sortorder=descending

Lots of possibilities. Find a shop versed in "diagnosis" and not parts replacement. An hr. or two of shop labor by way of a good tech should get to the heart of the matter.

Good luck.

Would it be a faulty fuel pump?

There maybe some moisture in your fuel tank. Once I sent my wife's BMW to a mechanic, paid $500+ for a new oxygen sensor and tune up that did not fix the problem similar to yours, a bottle of $15 Fuel System Treatment did the work.

Good luck.

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J.H.
'86 300E