Odd Fuel Pressure Issue

I am working on a 2001 Mustang 3.8L V6, it starts with no issue and will idle for a couple minutes before stalling, if I give it gas it will stall out sooner. On the fuel rail it was only reading 5psi of fuel pressure as well which is way to low. At first I though it was the fuel pump as the vehicle was ran out of gas then sat for quite awhile. Once I put the fuel pump in I was having the exact same issue, but now I had a whole 8psi of fuel pressure. Luckily enough I have an almost identical car here as well which has no issues that I can swap parts between to test. I have swapped over a known good fuel pressure regulator along with fuel pressure sensor from this other car. The doner car still runs fine with the parts swapped with this one and I still have the same problem. I even went a head and blow out all of the fuel lines to make sure nothing was clogged.

Currently I am getting over 30 PSI of fuel pressure from directly off the fuel pump, new fuel filter installed, and getting over 30 PSI of pressure where the fuel line connects to the fuel rail but still only getting 8 psi off the rail. I have even tested the pressure meter on other vehicles to make sure it wasn't malfunctioning and was getting good readings. Is it possible that the fuel rail itself is clogged? I don't have any misfiring or anything when the engine does start and it runs smooth so I don't expect any injectors are clogged.

I am getting a code that the Fuel Pump DVR is offline regardless of which one I am using in this car and neither one throws a code in the other car so I don't expect this to be the issue either.

Any help is appreciated.