Well I finally went and bought a fuel pressure test kit and found that while the pump was still working, it was only putting out about 15psi. I put a new pump in and she's back up and running now.

Funny thing though, I still don't hear fuel draining back to the tank through the pressure regulator like I'm supposed to when the Fp diagnostic jumper is used. And it is still doing that strange studdering thing that was happening prior to it quitting.