W124 Bad mileage, hard cold start, irregular idle
 

I have a '90 300E auto. Had it for two months. I've noticed bad mileage, hard cold starts and irregular idle speeds of from 600RPM to 15000. I've read on here that the OVP, Idle control valve, oxygen sensor, coolant sensor and air flow meter could be the culprits. This engine has no emissions equipment (ie air pump, or EGR) Any other ideas? I'm cleaning the ICV and checking the OVP today so I'll let you know on those.

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