No disrespect chaps but disconnecting the battery will do fuck all !

Phil you need to remove the KAM fuse on top of the fuse box its a yellow 20 amp bugger for 30 mins

KAM = Keep Alive Memory

Pull that bugger out and it will reset the ECU
Then you need to start allow to idle for 20 mins so it learns its new values then go for a drive should sort it


Regards Doug .