Rally fan 555

iTrader: (7)

Hi Guys = any ideas for this issue, I have an '03 WRX NB-R JDM Auto/Sport Shift with Steering wheel "paddles". Fitted with Dual Port BOV(Turbosmart). Runs on Super Unleaded. Recently the boost drops off at about 3k revs and the engine "stutters" as if I'm running out of fuel - then as the revs steadiy build boost returns and the car will acelerate fine-until the next gear change. I have had the engine checked and no faults have been diagnosed, checked for oil overfill/boost solenoid - no problem there, 1 plug was checked appeared normal ( I don't know about the other 3 !), problem is worse in full Auto mode but is less apparent when shifting using the "paddles" - therefore the garage suggested it was a gearbox prob ?? I have had the car for around a month now - the last week or so this "fault" has reared it's head - recently the car had a new "Lambda" sensor and has a new battery ( I mention that in case you think some settings have been wiped, as apparently the gearbox learns your driving style ??) any ideas, I tried to expalin as best I could with regard to the "stuttering" or hesitation when I put my foot down ????????