mids_muscle

Hi guys, new to the board.. looks to be good
Right bought an impreza wrx the other day... ive had a good look around, and this is what it has:

Uprated Manifold and Downpipe, large bore stainless exhaust
HKS induction
Front Mounted Intercooler
BOV
ProVA ecu

However.. im hitting fuel cut in 5th and sumtimes 4th.. any ideas why?
Until today I didnt know i had the pro-va ecu.. so havent been running octane booster, is this why?
Would fitting a bleed valve cure my problems or is there another simple solution?

Thanks for your help, look 4ward to becoming part of the community.