I hope you have solved the problem by now but if not try this: You mentioned it quits as if the kill switch were used. If this is accurate, I have never seen fuel starvation do that, it always sputters first. This makes me think the points spring is not allow-ing the points to close at the higher rpm and the juice to the coil is interuppted. Does it do it in neutral if you rev it above 3500 rpm? check the points.