while doing the head gasket I droped a bolt from the water transfer on the end of the head, just thought it had fallen into the grass and gavel below never to be seen again. How wrong was I, it had gone into the bell housing, making itself present, about a week later, by knocking a small hole in the gear box and liberating all the gear oil. Still managed to drive it home 35k's and then back into work 50k's to swap in the spare. All's well now.

Although I still have the slow return to idle issue

At start up it will intermitently blow puffs of white smoke and miss fires, I think it could be a leaky injector.

Steve