Hello, I have a 1998 Dodge Ram 1500 4x4 5.9 (Gas). This thing has several problems and I've went every way possible to correcting these issues and came out with little to no result. My symptoms are: Rough Idling, oil pressure gauge drops to 0 after it's warmed up and under 1400 rpm, check engine light is coming on for o2 sensor.

the truck has a long list of new parts: Oil pump, oil pickup tube, Cap & rotor, tps sensor, iac sensor, map sensor, oil pressure sensor, o2 sensors, spark plugs and wires, alternator, water pump, intake manifold gasket, plenum gasket, tb gasket.

all of those parts have been installed in the last 3 months.

It has all the same problems it's had with all the new parts installed, I'm thinking a bad ground somewhere or a bad ecu? What do yall think?

 

Replace the oil pressure sensor. That should solve the gauge problem.

What I don't see there, is have you checked the plenum yet? Might wanna pull the throttle body, and give it a thorough cleaning, if you haven't already, and while it is off, take a look into the intake. Is there oil pooling at the back? Then you need to fix the plenum. It's a standard failure on these trucks, and will cause a fair few of the symptoms you describe.