I recently swapped motors from junk yard.

Oil Pressure gauge light comes on with a reading of zero on gauge itself when the truck is idle only when HOT. When accelerate from idle it goes back to normal and gage light goes off.

It will do it multiple times during slow bumper to bumper traffic. It will be non stop actually. Morning start ups is fine reads about 40 psi. It only does this when engine is fully warmed up and at idle.

I already changed the oil pressure sensor unit and changed oil and filter to good brands and still same issue.

I read a lot about the issue and i'm thinkin the worse case, that my cam bearings are shot and it's only matter of time until engine dies.

The engine itself sounds good to me and when oil pressure drops to zero, it still sounds good.

Im lost here, does this sound like a worn engine? Because i think it would be fair for the shop to replace it with another used engine.

I want to change the oil pump but i cant keep changing parts with no results. I guess i can buy a oil pressure gauge and get a true reading.

Any idea what that sounds like?

could it be just the oil pump?