gabzor, a rough idle could be due to a failed coil pack. The best thing you can do is take your 1993 300CE to a reputable indy who is MB-trained and is familiar with that particular car. Get his professional opinion on exactly what is needed to make the car right with an itemized material and labor cost for each item. Then you can decide if it's a good idea to invest any more time and money, or sell the car as-is.

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Fred Hoelzle