The random nature makes me suspect a failing:

Crankshaft Sensor, Rear
MB# 002 153 92 28

and/or

Overload Protection Relay
MB# 201 540 37 45

and/or

E.H.A. Valve (Electro-Hydraulic Actuator)
MB# 000 070 39 62

Mercedes-Benz Driveability
Evaluating Electronic Engine Controls
by Steve Brotherton, Import Specialist
Published in: ImportCar, February 2001
PeachPartsWiki: Mercedes-Benz Driveability

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