Hi everyone thanks to all who imputed to this mystery. Well I've change distributor for a genuine vw Bosch item. Got it running no misfire like the one I described, but also learned that coolant bottle cap may be causing coolant system to pressurise causing a hot spot in engine thus mis fire will happen.
I only have one more mystery to solve and that is co potentiometer there is no adjustment. This is second unit I've tried an can't believe 2 different units failing.how ever going to buy a new one from bar-tek.
