1.8t oil pressure

[John Cody Forbes]

I'm working on a '01 Passat AWM 1.8t. A few weeks ago it had no oil pressure so I pulled the pan and replaced the pickup tube which was clogged full of crap. While there I cleaned everything up a bit and also pulled the cams, cleaned the head, and replaced all of the top end seals. Then reinstalled the pan, ran the engine with crappy oil for an hour, pulled the pan, cleaned it out, cleaned the pickup, and final assembled the car. When completed i verified plenty of oil pressure. Yesterday while on an errand the oil pressure light popped on again. Upon stopping the lodgers were clattering, so I knew it had no pressure at all and promptly called a tow truck. 

I drained the oil through a rag and found a bunch of fine black crud particles. Pulled the pan again, but the pickup isn't clogged. Then I pulled the pump which is in good shape and the pressure relief valve is not clogged nor stuck. 

Any experience or ideas? Is there another relief valve somewhere down stream?

-Cody (mobile)