i have a 1999 UK T/B de-cat full 3" and a green air filter may have a Chip as well in the ecu ??, has new plugs and leads fitted. starts and runs brill no missing at all. But when I slam my foot down to pass cars etc... it seems to miss or hold back once or twice? but after that pulls it away fine. it only happons when I am going 35/50mph ish.. then drop down to pass and it holds back just for two or three sec's? will go well over 130 with no missing if I do not floor it very odd ?
will a new MAF help me ??
ED

 

what make plugs and what plug gaps.. are the leads original or after market (crap).

do you have a boost gauge? what boost is it running?

is it misfiring holding back or just lower boost.. there is the sound emissions thing that drops the boost in 2nd usually.. if you hold it in 2nd at part throttle and then floor it you only get actuator pressure.

Simon