2000 BMW 323i Rough Idle, poor acceleration

Twice now the dash lights for Stability Control, EML, and engine icon have come on with accompanying rough engine and poor acceleration. Towed to dealer. Reset codes, said car was ok. Drove home, no problems. Next day, after several stops, about a 30 minute trip, all three dash lights came on again, same rough engine and acceleration problems. At the dealer now, can’t seem to pinpoint problem or experience the symptoms themselves.

Any suggestions.

First thing I would suspect would be voltage control - either a spike or dip in system voltage can drive these computers nuts.

I would clean connections at battery and alternator and engine ground (should be near right motor mount, I think) and plug a voltmeter (preferably an analog meter, or a digital meter that stores the high and low readings) into my cigarette lighter and monitor the voltage.

If the battery is more than 5-6 years old, you might want to replace it as a routine maintenance item.

Thanks for the suggestion on a way to go with this problem.

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.