I've posted this problem before but I'm doing it again with more specifics.

The car: A 1991 300SL-24 with 54,000 miles

What happens: Start a cold engine...drive off....about the EXACT time the car reaches full operating temperature, RPM's will drop to 0 if I remove my foot from the gas pedal. If I apply pressure, no problem. If I let up on the gas and the RPM's drop, and I quickly apply gas, the RPM's pop back up. This will happen for a few minutes then the problem goes away. The rest of the drive is fine. This only occurs periodically and I thought only in hot weather....but, I took the car for a walk during a sunny but 35 degree day last week and the same thing occured! If I come to a stop, I have to restart the car. Starts quickly if I hold the pedal to the floor. Has some starting problems if I don't hold it down.

This has been going on for two years and doesn't always occur. Only an irritation as I have to drive with an eye on the Tach when I slow down. But...becoming a major mystery!

Keep in mind, this ONLY happens about when the car reaches full operating temp for about three minutes...then all is OK. Usually about three to seven minutes into the drive...and never again that day??!!

Have replaced:
Overload protection valve
Auxiliary air valve
Lambda sensor
Cleaned fuel injection system

Any ideas???? What would you look at next?

Thanks, Jim

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Jim