It does not sound like your OVP relay. If you leave the OVP relay plugged in and Rev-up the engine to 1500 RPM, I believe that you will get the same effect as if you removed your OVP relay, i.e.: the engine will smooth-out.

I think you need to look elsewhere, but not sure where. Lots more diagnostic effort is required.

The logical place to START would be Spark-Plugs, Ignition System, Fuel Injectors, and other fuel delivery related systems.


Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]