Oil pressure problem

[vtv6]

Hey guys I'm thinking my bearings a stuffed in my rebuilt motor because I installed a oil pressure gauge the other day and it sits at about 20psi when you first start it but after a little while the revs drop down on the motor and the gauge sits around 10 or 5psi, plus when I take it for a drive it sits around 20psi but when you accelerate or speed up its goes to 40psi but when I'm sitting at the lights it drops down to 5psi maybe 10.
Could it be that the double row timing chain is scraping on the oil pump because I put the stock timing cover back on and didn't allow for the clearance issues I have read about. or could it be the oil gauge dose it matter where I hooked the neg up 2 mine from the gauge goes to the earth on the battery while the one on the sender goes to the block.

Thanks guys sorry if that dose not make much sense

[Cashman_309]

First check the wiring. Then try another gauge, preferably a mechanical not electronic, just to check and make sure first

[vtv6]

Will do taking it to a mechanic today thanks