light load surge finally nailed

[rb3221]

UPDATE.

Well after trying everything that everyone suggested and having no luck. I decided not to touch it at all last week (also had other work on), well bugger me dead the mate come over yesterday and took it for a run to see how bad it was and it did not do it at all it ran sweet as, so I still did not know what was doing it.

So now he going to take it for a good run on the weekend and see if it comes back.