How do you know it is running too rich? When was the last tune-up? When was the last time the O2 Sensor was changed? First I would verify it is running rich by checking the duty cycle(Lambda), then I would test the O2 sensor. Search and you will find how to do both.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....