Had the same problem wit my w201, it would die after a few minutes of driving and refused to restart until it cooled. The Fuel pump relay was overheating causing one of the switches to move out of operating range. Resoldering it worked, but only for a while since the IC board had a huge burn mark on it. Replaced it and the problem was fixed.

There is an easy way to test this by jumping the fuel pump relay, I don't remember the pins exactly, but the manual will tell you what to do.

xp

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1985 190E 2.3L - a constant project.