Tipped a can of BG44k in to the tank and filled it up, whether or not it does anything we shall see, but it was cheap enough and I don't know what petrol the cars been ran on for the last 12 years. Since I've had it its only had premium but I figure it couldn't hurt to try and clean it a bit. Seems to be the only cleaner with a bit of science behind it too, but again no loss if it does sod all!
@Invertigo did this turn out any good?