Alright, for those of you still interested, I made "progress."
I replaced the fuel filter and reset the fuel pressure with the line clamped. It definitely ran better, and I could randomly accelerate full throttle too. However, it would also randomly cut out like before still, and I was randomly losing fuel pressure altogether.
The previous owner installed a second external fuel pump that was rated at 35 gph (roughly 135 lph) which I had taken out, simply reclamped the lines back to stock config. HOWEVER, there was still the wiring he did. The pump ran a second set of wires up to the trunk, and I'm gonna do my best to explain this setup:
MY fuel pump positive from the coyote pack goes to the inertia switch, which then puts out a purple wire. I do not know where this purple wire is supposed to go, but on the opposite side of the trunk, the guy found the wire and spliced into it, connecting another wire to power a Hella Relay (4RD 960 388) which had a ground and two other outputs. One yellow wire to the external pump and another to the internal pump.
If you understand what I described, then you should understand what I was thinking when I decided to simply connect the original power wire to the fuel pump wire and call it good. I cut off all other connections to the relay in the trunk and I have 11.37v all the way to the pump wire. It ran for a few minutes, but the fuel gauge was very jumpy until it finally cut out. I now have no pressure at all. I can hear a slight hum from the fuel pump but I do not build pressure. I reconnected everything to the old setup and still nothing.
Perhaps the relay served as the pump's ground, but that doesn't make sense since there was no ground wire for that pump coming into the trunk, just the power wire going out. I honestly have no idea at this point. I'm hoping that the new pump isn't garbage, but we'll have to see. I want to hear everybody's ideas for now.