I'm having some issues with my 96 Honda Shadow Spirit 1100. Starting in June or so, it started stalling at idle unless I either choked it or kept on the throttle. I adjusted the idle knob on the carb and raised the idle. That seemed to solve that problem, but now when I shut off, I get a small, quiet backfire. If I choke it when I start it, the backfire is worse. I've tried backing off on the idle speed a bit but then it starts sputtering and stalling again. The bike was tuned up at the end of last season, it has had about 2000 miles since, oil is fresh as of the beginning of the season. I use 93 octane gas.