I have a 2008 xb12r that seems to run okay but not great. When I crack the throttle sometimes from initial take off it can sometimes backfire through air box and won't lift the front end unless I clutch it or get on it at high Rpms in first gear and definitely not in 2nd. Also the idle seems to fluctuate lately between 1200 and 1700. This stuff doesn't happen all the time but pretty often. Replaced injectors with oe injectors, fuel filter, plugs, and wires, new battery. Only things aftermarket is gutted muffler and K&N filter. Don't know what to think. Could use some help with this issue. Maybe someone else has run into this issue. Any help would be appreciated.