I've recently gotten a 99 yamaha big bear 350 2wd. I've started rebuilding it and it's got a problem. The bike idles fine but just as soon as I give it any throttle it kind of "sputters" but will keep running if I let go of the throttle. But if I hold the throttle long enough it will completly shut off. Anyone know what might be causing this problem? Thanks in advance it's greatly appreciated.