First I'd check ignition, especially the distributor, rotor and coil. On my car (92 300TE), a random stalling, as if it was starving for fuel, turned out to be a bad rotor. The fuel pump relais might also give you such symptons (integrated in MAS unit for your car), I have read that on this forum quite a few times. Regarding the OVP, wouldn't the car still run in limp mode even with a bad OVP?
Good luck, Bruno

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1992 300TE 160 kmiles