Timing and ignition

might be worth running it in the dark ….see if you can spot anything shorting across , maybe a plug lead earthing  to engine block ect …..

im with jim - you shouldnt be getting a shock - sounds like a lead arcing out - it wouldnt account for a high idle, but would do for a missfire

have you put new leads on it?

A cam such as a kent will give a lumpier idle than standard so dont expect to get it purring - its part of the comprimise - poor idling and lack of bottom end vs good power up the top

That's the point of this post mate, it's reving it's nuts off on idle :s

I've ordered some new leads but they cos a bomb

Have you slowed down the idle with the idle screw mate?

Yeah mate, I've screwed it all the way in.

You've got air getting in somewhere, have you checked the auxiliary air valve, just squeeze the hose. What about that adjustment on the throttle valve, sometimes the butterfly stop is mistaken for the idle control. If it were me I would do a comporession test next, the misfire sounds even and it could be a valve.
The only way I can see you could get a belt off the engine is if you were touching something on the HT side of the coil with one hand and brushed the other across something earthed.

Hahahaha, found a snapped clip on the idle air controle valve pipe :s dropped the revs as soon as I nipped the pipe!! I'll take it for a spin and let you know how it drives