help!! GMC C1500 engine oil pump problem

I was just wondering if anyone has any advice for me with repairing my oil pressure problem.

The oil pressure is fine when the engine is cold, but when the engine warms up, the oil pressure drops down to zero and the red dummy light comes on whenever the rpm's drop to idle speed. When the rmps are brought up, the oil pressure on the guage goes back up and the red indicator light goes out.

Does anyone have any remedies I can try before I remove the oil pan and replace the pump.

I am thinking that the screen may be gunked up and the pump partially worn.

Any helpful comments will be apreciated!  

you didn't say how many miles or what year your truck was. anyway sometimes depending on mileage a simple cause could worn cam bearings, or as you said a bad oil pump good luck  

Although your indications are of a tired motor, I'd first check your pressure sending unit -they can fail in different ways or could be restricted (could be leaking or internal contacts bad)  you could install a tee fitting and hook up oilpressure gauge to determine if sending unit is failing.