Impreza turbo 2000 uk 1998 low end hesitation
 

As title i have a 1998 uk turbo which is hesitating/surging at low revs up to around 3300 revs,now the history of the car is as follows

Car is pretty much standard NOW,with the exception of ported standard headers and up-pipe,but did have the following fitted until recently,Apexi power fc ecu,sti 8 intercooler modified to fit,walbro 255 fuel pump,and decatted exhaust from turbo,and all mapped by Jolly Green Monster.

Obviously replaced all the performance items with standard items including the ecu which i had kept the origional,ever since reverting back to standard spec,i have a hesitation/surge/pulsating of power in the low rev band up to about 3300 revs,so far i have replaced vac lines,spark plugs and gapped them to 0.65,leads,standard dump valve and pipework to dump valve,coil pack,and reset ecu each time i have replaced these items.I have cleaned out the boost solenoid,but don't know where to go from here,the car idles fine,and runs fine apart from this,it is just so annoying,the ecu which is an 8s is not showing any fault codes either
Can anyone shed some light on this ? :(:mad::cry:

I have the exact same problem, did you ever solve it ??

My 00MY UK car used to do this. Are you running in on standard unleaded?

What about the MAF?