My arctic cat 440z has been cutting out at low rpms, and fouling one cylinder's spark plug on a regular basis. it also idles just fine. and when it cuts out it will kill itself unless i either let off the throttle or pin it. i read online that these symptoms would make sense if it were running lean...but i have no idea how to correct this. I took the carb off for the cyl. that keeps fouling plugs, and it was very clean and seemed like it looked good. any thoughts on how to fix this? or if it is indeed running lean?