ok, long story short, motor went and dropped a long block in about 15,000 miles ago.. now I am having oil pressure problems. while truck is in Drive and at a red light, the oil pressure light flickers on and off but the oil pressure gauge isnt moving. Its about 35-38 PSI. now when I drive and taching 1,000-1,600 RPM the pressure drops down to 20-30 and bounces around and no oil pressure light. anything over that its fine i dropped in over $4000 in the motor alone (old motor about) now and i am very fusterated just trying to get it running correctly. Its all stock. It was doing the same thing as i have explained the last time the motor went and it turned out that CYLINDERS 3 AND 4 ROD BEARINGS GERNADED and allllll the metal shaving were blocking the screen in the pick-up starving the oil pump when idleing. now when driving everything was fine because it was forcing oil up threw the motor cause of more RPM.

now i dont know if its a bad sending unit but i know there are 2 of them and the odds of both of them going are slim to none. So now i am leaning toward the oil pump hopefully. anything would be appreciated. Thanks in advance

 

Stick a mechanical gauge on there to find out if the oil pressure is what it should be. It probably is, but it's best to be sure. If it's fine, swap out the oil pressure sending unit.