My'95 C280 revs up to over 2K rpm when starting cold. It immediately idles down to normal, but it makes a lot of noise and makes people look when I start it in public.

The check engine light has been on for several months after several attempts by various garages to fix the problem. The car has had O2 sensors, MAF, vacuum box, head gasket- you name it and it still has the CEL on. The over-revving phenomena is fairly new.

Any thoughts on the revving problem? If the car is warm, it starts without the over rev problem.

Thanks in advance.

BigLar