Oiling/oil pressure issues

[Steverino]

Hello guys, 

Another 5.3 with oiling issues... AFM equipped. 184k miles. New cam, lifters, oil pump, sender, timing chain, phaser and bolt, full synthetic oil. It would all work for about 2 minutes after warm up then fall to 0psi. Put a PF63 on it and oil pressure acts way better, so I added a little more than a quart to oil to see what that did. Now it stays between 20 and 

40 psi. I noticed when it would drop to 0, I could shut the motor down for a few minutes, restart it, and the oil pressure is normal again. By normal, it would go to 45psi and drop to 40psi, then slowly fade away. My question is: What could have made both rockers on cylinder #1 not get oil until 20 seconds after startup and continuously tap (BOTH)? And yes, all lifters are in the correct position... Thanks in advance!

Edited August 9, 2022 by Steverino
Didn't proofread