Fuel pressure specs

Hello,
After a 2 year sit, I decided to get my 1993 Maxima running again. I had less that 1/4 tank when I parked it but forgot to add any stabilizers. So it would run but very badly with additives and I took it to our local mechanic (NAPA auto repair). They found that the gas tank had a lot of sediment and sludge in it so they replaced it. They said the fuel pump worked great (it's only 3 years old) and I drove it home just fine with a fresh tank of gas. At around the the 900 mile mark from the repair, I started having the car cut out and stutter while driving. I've found that I can shut the car off and it's fine once i've let it sit for a bout 30sec-1min, but it starts acting up again after a few minutes. This gets worse the lower the gas tank gets. If I top it off, it runs fine until I hit 3/4 tank then starts the stuttering again. I'm guessing that somehow the fuel pressure is dropping just from the weight of the gas in the tank getting lower, but how would one figure this out for sure?

1994 Nissan Maxima 6 cyl Automatic

How do I check the fuel pressure? I was unable to find a check valve on the fuel rail. Thank you

Sometimes engine will not start. When it does, it runs fine, no stalling. I have replaced fuel filter, pump relay, and checked vacuum line to pressure regulator. Thumbnail check said to remove line from filter to regulator to see if gas was in line. None, which points to pump. I turned key on with line disconnected and in gas can, no gas came through line. The pump is only 2 years old, but aftermarket. I have no diagnostic equipment and nearing broke.

Where do I find the fuel pump, fuel pressure regulator, and the fuel pressure relay.