My just over six month old 570 Sportsman started stalling out occasionally going up hills after it had about 700 miles on it. Started doing it more frequently and now has a very rough idle and sometimes dies and will not start again. Did all the usual, changed air filter, replaced with new fuel, even changed oil. No water in the oil or gas. When it first started stalling out I put in fuel injector cleaner and it ran good after that. Once that burned through the gas tank and I refueled, it started stalling out again and started running real rough at idle. If it misses going up hills and I hit the throttle it goes real good. Now it misses badly while idling but again if I give gas it smooths out and runs well until I let it go back down to idle. Any ideas would be appreciated.