I had this problem to, got stuck in Vegas for 3 days while the dealer worked on it. They fixed it, I drove off and the car stalled 400 yards from the dealer. After getting the car back, it was determined that it was the fuel pump relay.

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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.