hey all. im pretty new to the wrx scene and was just wondering if anyone had the same issue's as what i have...

about 2weeks after i bought the car it seems to misfire and backfire hard out once it has been driven for a little while, i have noticed mainly between 2000-3000rpm? it seems like the car aint getting any fuel? still idles well, car has the following modz:

k&n cai
exhaust turbo back
boost controller (7psi)
139ks on clock
aps tmic (thick bugger)
sti bov

other then this its stock

so far i have done major service (oils, belts, coils, fuel filter, ngk leads, subaru upper engine flush, ignitor, platnium plugs, battery, afm, sti bov, ecu(2nd hand), new alarm, injectors cleaned........ and it still does it

all of the parts are brand new except the ecu and it still does the same thing. I have ordered a new walbro pump and 02 sensor, so once they arrive i will fit and see if any diff.

is it possible the 02 sensor is stuffed? any help would be greatly appreciated.

Mike