Ive been helping a friend with a 2006 Sportsman 800 and its problem started off with a really bad hesitation off the bottom end like it was too lean and back fired through the intake really bad. I did the usual checks like fuel pressure, Tps adjustment, clean the throttle body, and the only thing that helped was unplugging the t bap harness and it made it run near perfect. When I replaced the t bap sensor and did the repair harness it made no difference unless it was unplugged still. I did some more checking of the wiring and saw the connector from the crank sensor by the ecu was dirty so I cleaned it and it made the bike run great again with no bog. The problem I still have is that while idling it will randomly give off a slight back fire though the intake and die. It starts right back up and seems to go away when its good and warm, but I feel it should still idle smoothly and stay running while warming up. If anyone has any advice or things I could check it would be greatly appreciated.