Hesitation, surging and crap mpg.

[Lawrence]

I'm thinking more along the lines of coil pack(s). Less noticeable above 6k Rpm due to changing over to main jets on the carbs......just my 2p worth.

Could be, would be worth finding a known-good set to try out.

I'll do a compression test too at the weekend, may well not have the time before then.  I have run it without an air filter to see if it was that causing the problem but it was exactly the same.  Looking at my notes the air/fuel filter were done 21k ago so probably due by now