08 tahoe 5.3 low oil pressure after filter & pump change
 

hi,

I had the issue with the drop in oil pressure when engine is warm.

replaced the pressure filter (which looked clean when replacing)

still problem existed.

now we have changed the complete oil pump and it still has the same issue.

if all the above did not help.. what else could it cause??

I had some issues with AFM failure in past and it has been disabled in the computer.

excessive bearing clearance from a worn engine is one possibility. only way your going to confirm this is to tear down and take measurements. cheap fix is to run a heavier weight oil.