I have a 2003 Trail Boss 330 that I bought my daughter. It was running great the all of a sunden it started acting like it was running out of fuel when she pushed the throttle. still Idles great but it will bog and backfire through carb when giving it gas. I cleaned out the carb (4 times) new spark plug and fuel filter. Swapped pump with a good running atv. swapped coils. I am at a loss. Any ideas>