Thanks for the tips guys. I have to admit that it does sound like a TC issue now Ive read up a bit, but mine seems to have some differences to what people have been describing. The "Miss fire" only last for a second or two if you keep gently accelerating. It becomes more prominent if there is a load on, ie my trailer. The gearbox changes are as smooth as silk up and down with no clonking. Going up a gentle incline with the trailer on and getting the speed just right I managed to get some faults registered which where all " missfire on cylinder x" and multiple missfires. so I am sure its an engine problem rather than trans. Ive ordered up some new O2 sensors as the existing ones look original and Ive got 130k miles on her now, so we will see if they have any effect.