Got my Triumph America out of storage this afternoon, Happy days?

Well, almost!

Going down the road & it started to die so i flicked it over to "reserve" & all was good again. Went to garage & stuck £20 worth of fresh fuel in & flicked the fuel tap back to the "on" position. The next 15-20 miles of the journey home was good, but then, as i was red-lining it through the gears from the traffic lights, it developed a massive flat spot & had no power?
I pulled over, switched it off & started it up again, misfiring like mad & sounded like it was only firing on one cylinder. Pulled away & it struggled to hit 60 mph. On the straights the power would cut in intermittently for a split second then go again, on right hand corners & roundabouts the misfire disappeared but came back again on exit of corner/roundabout?

Im thinking either... spark plug, HT lead or coil pack? What do you guys reckon? Managed to nurse it home with no power, popping & banging like a sh!t house door in a storm!


Proper Prior Preparation Prevents Piss Poor Performance