Got a new guy in at work who is mini mad, we checked the timing, leads, HT etc all to no avail.
Then he checked the spark plugs again, No 4 was very wet, he did a compression test on it - ok
swapped the sparkplug over to another cylinder and the symptoms changed.
Put a new spark plug in - problem sorted grrrrrrr
Thanks Trev
I spent hours on this fault and probably could have fixed it on day one and used it all summer.
Still just got to get it ready for the MOT now and next season
Thanks for all the advice anyhoo
Griff