Fuel pressure problem

[flattype]

Losing fuel pressure at WOT. Under full boost (around 17-18 psi) The gauge (autometer pod mount inside car) will jump to around 60 then drop down to around 45. I replaced the walbro 340 with a new one around 6 months ago because it was shot. (losing pressure down to around 15 at idle) I dont have a hot wire kit but i just ordered one. Need help to diagnose this car has tt chip te44 turbo 42 lb injectors 3inch downpipe etc. Thanks Eric