Hi all, I have a 1992 400E that has a strange running problem that keeps gradually getting worse. When the car is started cold, it runs fine, and drives fine... for about 10 minutes. Then it starts misfiring and running rough/bogging down, and more recently backfiring in the engine compartment. After about 5 minutes of this, it clears up and then runs fine for the rest of the day. The last thing I did was clean the MAF sensor, but that didn't seem to make a difference. This seems to be an engine temperature related problem. Spark plugs are recent, wiring harness has been done, fuel injectors have been professionally cleaned. No issues with ASR, no error lights on the dash, though I don't have a Check Engine light on the car.

Anybody have any ideas?