I don't know how you store your fuel but the chances of it going bad are pretty slim. Manufactures started using anti foaming agents in there fuel and you can't make it foam. Several years ago foaming was a problem, not so today. If it isn't junk in the carb as Ken mentioned then it wa probably a tune issue. LAs break in very quick and don't require a lot of break in. As the Jester mentioned, about 400 rpm below max.