Got stuck in the mud on saturday and red-lined why trying to get out. Finally made it out but with a change to the engine. It is idling real rough, but it starts up with no problem. Oil Pressure down to zero on gauge. After reading some of the previous threads it seems the lpop runs the oil pressure gauge in the dash. But i dont think a bad sensor would make the truck run rough. Could it be the hpop which might of gone out? No codes showing!