I have a 2011 Polaris ranger 800 xp and recently it started to idle up and down every now and then. I will be just sitting there and rpms go up like I hit the gas the goes back to normal after a couple seconds. If you just let it sit there it will do go up and back down. After a few seconds it will do it again. Sometimes it won’t do it at all. Any idea on what it could be.