Get the car hooked onto an SDS and read the codes and adaptation values. That should give you a very good idea of what's going on before you shotgun parts at it. However, I agree that that symptom is pointing toward a crank position sensor, which is a common failure on M112 V-6 and M113 V-8 engines.

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John Shellenberg
1998 C230 "Black Betty" 240K

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