F90tlrd misfire and stalling at full throttle

[DRIFTWOOD]

Initially engine was overheating. After new water pump and thermostat, found multiple pieces of an old impeller throughout the engine, Also replaced the thermosensor with tested defective with resistance test. Now no longer overheating. Also replaced hp fuel pump thinking it was failing. However, engine begins to misfire and eventually stall shortly after full throttle, and about 5200 rpm. YDS shows no codes. Good compression and spark on all four cylinders (at idle at least) Fuel pressure about approx. 34 psi. Engine will run at about 2500 rpm. When it stalls out, it will start up immediately.

HELP!!!!!!

[99yam40]

I would monitor the fuel pressure when the problem shows up to make sure that is not the problem.
testing things while motor runs OK does not do much good

[DRIFTWOOD]

Already did that. No problem with fuel pressure.

[fairdeal]

34 psi rail pressure is right when the engine is idling
with throttle open should be ~43 psi

but if you are seeing steady rail pressure while the engine is "acting up" -
misfiring and stall -
then its not a fuel problem.

I'm baffled...