The oil pressure sender is not a terribly difficult DIY job and is a fairly common failure item.

You could either change the oil pressure sender and see if it makes a difference or hook up a mechanical pressure gauge to the engine and see what reading it gives.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record