Thanks for your reply

That was my first thought, I've put new plugs in, no change, if it is the coils why is it running at all? surely it wouldn't start or run very lumpy?

I took it for an 'Italian tune up' today and it runs great right through the rev range, plenty of power until suddenly it starts hesitating like I'm out of fuel, I can keep driving but it will cut out as soon as I stop, the revs drop to around 500rpm it hunts tries not to stall but eventually stalls. It will crank but not start until I floor the gas!! then run fine until it repeats the fault!!

Maybe all my coils are stuffed but sometimes work fine? which I doubt.