Cannonballman

Hey lads had my ba xr6t tuned on Friday by a "reputable" tuner and before then my car was running sweet, whilst it was at the workshop old mate called me and asked "how long has it been dropping a cylinder??? buggers me, seemed fine to me! Anyway he said that one of the spark plugs was cracked which had only been replaced recently so I got him to put a new set of ngk's in, problem solved... Took her home was running sweet 9psi tune lots more power didn't really get up her to much but could definitely feel the power increase, took her for another blat Saturday and it started, when I would stop at the lights it had a *cough* at idle like every 10 secs, then seemed to get worst as the day went on, now it's not only at idle it's also when it hits boost has a big dead spot at about 3000-4000rpm and then smooth after that! Cleaned the throttle body, checked all the clumps are up tight, still does it... Returned to factory tune and now that's really bad! Read a few posts on here and I'm leaning towards coils but the coils in it were replaced with factory coils at 60,000kms and the car has now done 85,000kms. Any ideas as I wouldn't mind fixing it myself? Cheers.

Where is the best spot to hook the vac/boost tube into? Cheers