1992 300E High Idle---HELP!!!!!!!!!

[190E2]

I have a 92 300E that is driving me crazy. It has a really high idle. I have read post after post with no success. I can't find a vacumn leak. I have changed the OVP 3 times. I have changed the idle air control valve three times. All the valves I have cleaned extensively. I changed out the MAS twice. OK, When I changed the valve, I cranked the car and the idle immediately went to 1800 rpm. I unplugged the idle valve and the idle came down to 1000 rpm. So I plugged the valve back up and the idle remained at 1000. I shut the engine off and then started it again and the idle immediately went back to 1800-2000. I then unplugged the water temperature sensor, both fans came on at that time so I figured it was ok. I also checked out the throttle linkage and found nothing unusual. Anybody have some suggestions? HELP!!!!!!!