I finally discovered the problem tonight (after replaceing 3 temp senders/switches, the battery and the overvoltage protection relay)
As I was driving I noticed that the temp gauge movement sometimes was in sync with
bumps that I would go over on the road, in other words if the car experienced some movement, the gauge would react at the same time by jerking up and down.
I poped the hood, had my wife watch the temp gauge in the car, I grabbed some wires from the temp sender and pulled them repeatadly, when I did she noticed that the gauge moved when I pulled on the wires. I figured it was a short. I took off the air cleaner, light up the area with a flash light while pulling the wires to expose them, after a bit sure enough I saw a joint with copper wire exposed. I cut off the damaged portion of wiring, spliced it and it works great now. Whew glad my car is back to its old self now. Hope this helps somebody someday.
This is a GREAT GREAT site.

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1996 E320
2000 C230 Kompressor
1988 190e 2.3 - 225K miles, owned for 7 years. I cannot say enough good things about this car. Very well built, even at 225 it ran like new.