Seems to come round every few months (was a different problem last time)... car not quite feeling as rapid, holding back before about 3000 rpm and doesnt seem so fast when flooring it. boost is cutting in and out slightly. The turbo is spooling up fine so Im pretty sure its not that (fingers crossed!). I dont think spark plugs have been changed for about a year and a half so im hoping its just that. Got some iridiums waiting to go in but am too much of a noob to self servicing i cant fit em myself!!! Guess it could be afm possibly as well.

What are symptoms of plugs needing changing?