I drive a 2001 Chevy Suburban 1500 4X4 5

I drive a 2001 Chevy Suburban 1500 4x4 5.3 V8. When I fire up the engine it starts to make a claking noise after idling about 10-15 seconds. It makes the noise then it dies off slowly as it warms up. Sounds like if the engine is dry and doesnt get lubbed until it runs for a about another 10-15 seconds after it starts making the noise. I had an incident with the oil pressure sensor where it wouldnt read any pressure at all and as it warmed up the pressure would pick up to normal. It happend a few times but it eventually went away. Would that have anything to do with it? Could the pick up be clogged or do I need another oil pump? What could it be? Thanks for your help.