high idle

[twojax]

I just recently replaced the motor in my 1994 C280 and its idling between 1500-1700 rpm when it warms up...when you first cold start, it idles and then shuts down..but it will start right back up and idle fine..but as it warms up the rpms rise to 1500...when the car is placed in gear the rpms drop to 700-to 850 rpm..the asr light is on and the check engine light just came on...the car runs great other than the high idle... I didn't have any of these problems with the old engine..I replaced it because of a blown head gasket...any suggestions on this are welcome