low oil pressure
 

I have a 94 5.7 z28 the car has never gave me a problem I parked in the garage for winter and pulled it out the other day . it had low oil presser and was having a hard time staying running. I changed oil and filter.i will have presser for a bit then it falls .it has a slight knock please help

The combination of knock and low oil pressure is not a good thing. This usually indicates a bearing problem, or a bad oil pump which will cause a baring problem. The problem with keeping the engine running could also be caused by a bearing seizing. With the engine hot, open the oil filler and take a good smell of the vapors coming out. If it smells like overheated metal, the engine is trying to seize up. Verify the oil pressure with a test gauge, so you will know for sure.

I may help to pull the filter, don't dump it out, dip you finger in an wipe it on a clean paper towel. look for small metal flakes.

If oil looks good then a new oil pump may fix the car. If there is a bunch of flakes the motor is in need or replacement/rebuild.