My XTX is on a 56 plate and that has an ECU number ending in -00.

I got fed up with the dealer in the end. I got comments like, "dont' worry mate, they all do that" and "everyone we've sold we get the customer coming back. They're all like that."

Upping the CO helped with the stalling and also rolling the throttle open instead of yanking it open smoothes things out.