Sputters under Full throttle
 

So i just installed an new fuel pump upgraded to an 255lph for future mods and now under heavy accell i get Sputtering any ideas what this could be it. car runs fine at cruse and idle

Car is an 94 Turbo WRX Import. also just replaced plugs gapped to about .9mm what a good average for turbo application i know its less

plugs are way too bit, commonly Turbo plugs should be between 0.65 & 0.75mm
what plugs have you actually fitted??
make sure the fuel pump is connected correctly because if the pipe is bleeding pressure back into the tank then it won't have enough fuel for WOT