OK,...I found this from MT-2500 on another post and I have posted my pressures below in red.
I am looking for confirmation if it is the fuel pump or the fuel pressure regulator or ?.
Hard to start cold.
Check cold start fuel pressure...key "on" 61psi then slowly drops to 40psi.
Check engine running fuel pressure.....53psi.
Check engine running on the road fuel pressure..53psi-62psi...57psi at cruise.
Then shut it off and watch for fast leak down...slow drop to 40psi & holds.
Pinch off at rubber part or block off return line and check full pressure..80psi.
A few engine have different fuel pressure specs.
But here is the guide lines for fuel pressure testing.
Most Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.
MT