Dear Snoopy572,
We both have the exact same problem/symptoms with our cars. What you have described is exactly what my car did. The electronic part that kills the engine is the idle control valve. I disconnected it. The vehicle does not stall any more and runs like a dream.

Before you go out and spend any money do the following. Remove the air cleaner. Once removed, you will see the idle control valve (looks like a 3 inch long cylinder). There is black wire on the idle control valve. Disconnect this wire.

The previous owner of my car spent at least $1000 trying to fix this problem. The mechanics changed everything from O2 sensor to fuel injectors and they still could not figure out the problem. She got fed up and sold it to me. My advice is try this first. I have been driving my car with the idle control valve disconnected for almost a year. I had bought an OVP but turned out to be the wrong one (For a 190E). If the problem persists take the car to the Mercedes dealership. They charge $90 an hour but they know what they are doing. The previous owner of my vehicle took it to a regular mechanic who charged her all the money but still could not fix it.

As far as I can tell you will need a new OVP. Let me know if a new OVP solved the problem, and also if disconnecting the idle control valve does anything.

(See my original post for drawbacks of removing the idle control valve)

FS