Chasing a fuel issue

[J-440]

Here's what I got. Stainless tank from Rick's, A1000 fuel pump (exterior mount), 2 filters, -10 feed line, -8 return line, Aeromotive regulator all going to an EFI 440. Everything is new and the pump has been rebuilt. The car fires up fine, after 5 minute warmup I take her out. Car dies because the fuel pressure starts fluctuating from 59psi down to 25 psi. I've had this problem before thinking that my charge wires from the alternator to the battery were too small...which they were. I've corrected that with 2/0 wires but the problem is still there. Nothing is kinked and the filters are fine. I'm just wondering after 5 minutes with another 2 minute drive, the fuel pump starts to fail. I have a fuel pump controller I can slap on but would that make a difference?