JRS3800 stated that he believes the oil senders can become flaky on our vans. He said that he has seen the oil pressure gauge fluctuate a lot even with replaced senders.He said it is not easy to get an accurate sender. He has not seen many failed oil pumps either. His experience is that the pump should last the life of the engine.
I found out that our fuel pump was going bad some time ago when I bought a fuel pressure gauge and measured 20 lbs at the rail. I remember very vividly dropping the tank with 5 gallons or more in it and replacing the pump. Obviously, I would consider checking the fuel pressure as well as the voltage going to the pump. I do not have schematics for the 3.8L TS, but voltage before and after the sender should be checked. I would think that a drop of 2 volts would likely affect the pump. It is more than likely that the pump is failing if it is original.....good luck..KEV