When the ignition is turned on, the idle control valve on my '93 190E 2.3 operates for 10 seconds then turns off. After the car is running, there is no change in idle speed if I unplug the ICV. When the car is warmed up for 2-3 minutes it idles and drives perfect. But, when starting it cold, it seems like the Idle Control Valve is limiting vacuum to the air flow plate and there is no vacuum at the Ignition Control Module until after 2-3 minutes. After that, there is vacuum at the ICM and if I unplug the vacuum line at the ICM, the idle drops.
I have all new hoses to and from the ICV and I removed it and gave it a good cleaning. It has a slight opening with no power applied.

The engine used to start up immediately and idle at 1000 rpmsfor a couple of minutes and drop to 7-800 rpms. Now during cold start-ups, I have to press on the accelerator for a couple of minutes until the rpms start to increase.
The OVP relay and fuse appear to be OK.
So my question is, is the Idle Control Valve supposed to remain operated during the warm-up stage, and then release or what??? If I apply voltage to the ICV it clicks and fully opens. But it doesn't appear to be doing anything during the start-up or even later when the engine is at operating temperature.

Any ideas?
Crank Position Sensor?
Coolant Temperature Sensor?

Thanks,

Dave

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible