I seem to be suffering a gradual loss of power on my S3, but struggling for ideas where to look! The symptoms are it seems to lack the same degree of boost it used to have, what boost there is comes in late, and the engine sounds quite rough under load. If I disconnect the battery to clear all and any adaptations it will go back to feeling normal, un-plugging the MAF can improve things too. Erratically it will occasionally run normally without having to do any of this. I've treated it to a new MAF recently, and a full service inc plugs but I keep getting the same symptoms. In particular the engine just doesn't sound 'right'. Any ideas where to start looking?