It just cuts out for a second or two when driving, on the odd occasion it surges, sometimes changing gear throttle release is slower.
Usually, when its been driven a while this all clears up.
Diesel leak from throttle spindle, I think. Ive cleaned it off and will run it up to confirm because the bleed screw was also wet, hopefully its the bleed screw! Old filter was clogged, running a lot better with the new filter on there.