hey fellas i need some help i cant seem to figure out the problem why i'm having low oil pressure. I'm getting solid red oil light so i changed oil pressure switch and that wasn't the problem, so i went ahead and installed an oil pressure gauge.
and the oil level is fine right below the top dot.

When i start the car up when its cold PSI is reading at 40 PSI idle as the car slowly starts to warm up the PSI is dropping, then drops to 8-9 PSI when the car gets warm then the oil lights comes on.

When I rev the RPM to 3K PSI its reads at 40-42 PSI. I turned off the car. this happened after i took my car to a shop for a valve adjustment.

Now im removing the oil pan to check things out is there anything that i should look out for? could it be the oil pump? pick up tube? if its neither any of these what could it be? please tell me what else to inspect besides the pickup screen and the oil pump. could oil filter casue low pressure? Thanks.

 

This started to happen after you got your car back from the shop for a valve adjustment? I'd be knocking on their door for some help.
I have seen people re-use gaskets coated with silicone and little bits have broken off and blocked oil pickups, and worse, oil passageways. H22 valve cover gaskets should be installed dry with a very small amount of silicone on the 90degree bends over the cam end caps.