I'm working on and LA 318. It has an after-market oil pressure gauge. I was driving home and thought I heard a quiet tapping sound around 3000 RPM. After about 30 seconds I could tell it was a tapping sound and I looked at my oil pressure gauge and it was bottomed out at zero. Immediately shut the truck off and coasted to a stop. Went and check my oil which was just fine and full. I went to restart the truck and no oil pressure again so I shut it off. I waited a couple minutes and tried again and the oil pressure went right up to 35 as normal. I drove the truck home with perfect oil pressure and then parked and took off valve covers and there was no signs of sludge whatsoever or blocked drain holes.

Since then the oil pressure will drop randomly and I'll turn the truck off immediately and roll my steering wheel around side to side then turn the truck back on and the oil pressure goes right back up to normal again. Is this the sign of a pickup tube getting clogged up with gunk in the pan or the oil pump failing?