I've heard of tired stators getting weaker with heat, but I don't think that's it. Since you have one, you could try though. Clean carbs by taking apart and removing all jets, needles,ect. use carb cleaner and compressed air. If you have stock carbs, don't interchange bowls. If problem continues, might need to start testing electrical system with multimeter. simple things to try are clip a 1/4 inch of plug wire off so your plug boot can make contact with some clean wire, of course new plugs also. keep us posted on what you find. welcome to BHQ