I've got a 2011 sportsman 850xp. When I first got it it idled between 1150-1200 rpms cold and when it warmed up. I replaced stock exhaust with hmf swamp xl. Also put 28" tires on. That's all I've done to it. I've put about 35 hours on it since I've made the upgrades. I've changed the oil and oil filter. Now it still idles 1150-1200 rpms cold. When it warms up after10-15 minutes of riding thru the woods/swamp when I pull over to rest a minute it starts idling between 1000-1250 rpms. It just slows down and acts like it will cut off then boosts back up then dies down again then boosts back up. Any info/help/advice will be greatly appreciated. I just dont want to let it go and be paying for a new motor or something after 3 months of riding. Thanks in advance!!!