OK,
long time since posts, I have been away a bit.
I have replaced all elec parts, rotor, plugs, leads dizzy cap and plugs.
In addition I have run decoke through the car. The timing is set and the idle is wound back.
It has made a big difference but still does it occasionaly. I think the "carbon in the cylinder hypothisys is correct".
Great advise from all, I am very appreciative but it looks like I will pull the head off and give it a clean up......gives me something to do at least.
And yes it is an elec dizzy.