Update to the issue..
Tried the wet finger test, seems to be slower warming up on 1 and 2 cylinders, so decided to changed plugs and caps to the NGK 8022 type. no joy still same, tested coils to spec in Haynes manual ok. removed tank and moved bracket that secures the coils and fuel filter, checked for splits in rubbers etc, none found, I have also run a some fuel treatment through which made no difference, I presume next stage is the carbs out?
Cheers.