Spannersrx7

I have been tuning my car for more boost and its going al well apart from at 3.5k it misfires under full load in 3rd and 4th gear.. after that its fine stays nice and rich till redline. doesnt do it first or 2nd so assume its to do with extra boost that can be produced in longer gears.. 550/660cc injectors 500hp bosch pump microtech lt=8 etc. goes to 14psi and comes down to 11psi by the time its at redline