i have a 94wrx decated, induction kit,dawes valve,dump valve,runing on optimax

in cold damp mornings seems to be worse engine seems like it is missfiring the revs try and die then pick up again to just over 1000 seems lumpy at times also at light throttle seems as if the car is holding back,seems to backfire through exhaust when changing gear seems more at light throttle when giving it a bootfull seems ok only a odd hesitation hear and there has anyone got any ideas what problem may be arising or it has

 

possible that the induction kit has messed up the MAF hence your idle is all lumpy and such...?

ScoobyDoo69

 

I'm with ScoobyDoo, MAF likely shot with the induction kit, else coil packs are tired with the age of the car. Could also be the Lambda sensor in the exhaust, search on here for ways to test each item.