1994 Pontiac Firebird fuel pressure regulator

Engine Performance problem
1994 Pontiac Firebird 6 cyl 145000 miles

i think ive got the car diagnosed with a bad fpr it is running with 20-22 psi when it should be at 41-47 pressure holds steady after key is off and I pulled the vaccume line off the fpr while running and had no raise in pressure so my question is this does this sound like the problem and if so do I have to pull the fuel rail in order to fix it. They do not sell fpr's for this car just a rebuild can this be done from the top?