Just got home (luckily) from a 150 mile ride. As I was approaching a stop sign, my bike back fired when I down shifted. It did this a couple of times then died while running about 30mp. Every time I came to a stop, it would do the same thing. I would have to keep rolling the throttle to keep it running. It ran fine on the highway at 55 to 60. When I pulled in the drive at home, it died again. Any suggestions or ideas? I would appreciate any and all. Thanks!