Mine had that problem before so I looked in my tear down manual, it was very thin in the carb section. I took it to the dealership and said tune it up( the carb only) cost me 38 bucks (1/2 hr labor + tax) now it works great.I'm mechanicly inclined but not a mechanic, was told you can really mess them up and get expense to fix.
food for thought :-/ :-/