Just a sticky switch, had it checked out pressure was fine (thanks Carnells of Enfield for dropping everything to check it when I turned up unannouced!)
Couldn't find my power commander after my house move - I think I've thrown it away!
I've ordered another and had a base dyno run done on Dynospeeds D/J 250 to see where I stand.
It made 153.8 BHP stock (SAE corrected) with 7500 miles on the clock, not particularly good or bad I suppose.
The run definately showed a number of weak spots at certain throttle openings which are causing my stutter, can't wait to get the new PCII and custom map, then (touch wood) I'll be sssssstutter free!