I got a fuel pressure gauge form Autozone loaner program.
Once I turn on the key gauge goes to 55, then slowly starts dropping to 44 psi. It stays there.
Is that enough PSI?
Technically, not on the original "spider" poppet injectors. I haven't looked in a long time, but IIRC spec was like 58 psi. Although both my old 4.3 and my 5.7 have always started just fine with 55 psi. I installed the updated MPFI on the 5.7 because I had a dead injector when I bought it. The MPFI can work with lower pressure.
The pressure drop is a concern too. You either have an issue with the FPR and or an injector that's leaking fuel. When that happens the fuel floods the engine and can cause issues with crank-no-fire. How long does it take to go from 55 to 44?
I've never tried this, but I've read once a guy opened the throttle body and primed the pump and saw with a flashlight a huge squirt of fuel getting dumped inside the intake! Massive flooded condition in that case.