FiTech EFI system

I have the dual quad, in tank pump, corvette filter/regulator.
My psi gauge is on the forward throttle body.
After running the car a while trying to diagnose a completely different issue, I topped off the tank to keep it above 1/4.

Last night my in tank pump decided to go from a regulated 58psi, holding there after priming, to 100psi when primed, making a horrible screeching sound, then back to 0, then banging off 95 when running.

The screeching sound was alarming.

Disconnected filter out line, turned key to run, no screeching.

Disconnected throttle bodies, blew compressed air back thru lines. Hooked back up, no change.

Unhooked forward throttle body, key to run, no screeching.
Only forward throttle body hooked up, screeching, psi crazy.

Moved psi gauge to rear tb, hooked everything up, back to normal.

Moved psi gauge back to front, still normal.

I think some debris was stuck in the front tb, and drained out when moving the gauge.
The lines come in the front, and when the key is off the fuel drains back out, but on the other side the fuel stays, and it drained out both when moving the gauge.

I hope it's resolved, but what would cause the psi to increase on the forward tb, and in turn make the pump scream?