I have a 05 Sportsman (carburated) that has an issue since new. When I get to 10,000 feet or above, the darn thing just will not get out of its own way. it sputters and chokes and has absolutely no speed. I have had it to 2 different dealers and 1 independant shop. the jets have been changed and the springs for the clutch have been changed. Does anyone have any other suggestions that might give me ANY power at altitude?? or do I have to trade up to a fuel injected unit??