From my previous post http://www.audi-sport.net/vb/a3-s3-forum-8l-chassis/178453-not-idling-properly-fluctuating-idle.html this is the same problem but different. Plus, that thread has gone off on a tangent.......let me explain...the above problem was cured from doing the N249 delete. It's come back now but not from normal driving only very fast driving then come to idle it's rough as hell, but not all the time. The idle is really rough. I get random misfires so it's not just one cylinder. I was thinking coilpacks or the spark plugs are duff? Is there a way of testing/checking the coilpacks? I don't want to have to buy them if it's not that. There is still the possibility of a vac leak but how do you test for it if it only happens after driving quickly. When I say quickly I mean accelerating hard onto motorways. It's not noticeable at cruising speed ie. 70mph once I've joined the motorway but when it comes to slowing down it's just at idle. Bit stumped really.