What did the shop actually find when they pulled the file? I'm asking because there's a difference between a box that just clips the rail pressure signal and one that also messes with pulse width and timing. If yours was only touching the pressure sensor, then yeah, the ECM never sees real fuel pressure, so it can't pull fuel when it needs to and you get the P0087 plus a pump that's been running dry. Did they say if your injectors got hurt too, or just the pump? That $600 diagnostic might be the cheap part if the CP4 was eating itself the whole time. Curious what codes besides the 87 showed up in the history.

Watched my buddy go through almost the exact same thing with a cheap glue gun from one of those bin stores. He was halfway through a gnome door hanger when the thing just stopped melting sticks, so he switched to wood glue and clothespins out of pure spite. His wife still hangs it on the porch every holiday, and nobody can tell the difference unless you get right up on it. Those budget guns seem fine for ten minutes of light use and then they just give up. Sounds like yours picked the worst possible moment to quit, right in the middle of pinecone city.