First off the car is a 1988 Firebird Formula 305 Vin Letter E. I've
picked up a new oil pump but when I printed out the repair specs I've
decided to try and get some input from the web.

I'm having an issue where on startup cold I'm getting around 30 psi and

that stays pretty constant until engine warms up, then I start to lose
oil pressure and eventually at idle it completely drops to zero.  When
I am driving I get about 15 - 25 psi but if I come to a complete stop
or slow down to a crawl I lose complete oil pressure and then I get a
knock that scares me. The only time it knocks is at idle or driving
really slow with no oil presure. I've decided to not drive it until I'm

sure what can be done to help the issue.  I am running 10w30 and I
believe the oil type isn't the issue. I'm afraid the oil pump might be
going out. Is there any other options that might be the issue before I
have to start the long process of changing the Oil Pump. Like maybe a
faulty pressure relief valve or a sending unit?

Thank you for your input