I took the battery out last weekend to help a mate and ever since the car will randomly stall when buttoning off accelerator meaning having my left foot on standby or just left foot braking while keeping revs up. It seems to be more of a problem once warm. Before the battery came out it had never stalled but did random rev when idling, when I asked on another message board about that and someone mentioned the Idle Speed Controller could be clogged. I have cleaned this the best I can and the random revving has decreased a little but not gone away.
Could taking the battery out have stuffed with the computer settings
somehow?

Really? What a pain in the a**, I had a very similar problem with our mondeo a while back, revs fluttering low then stalling if I wasnt fast enough, turns out that was the map sensor, could the coon be the same?

Will do cheers, wont be puling it out again anytime soon then.