I have a chain saw that starts and runs fine. But as i use it and it gets hotter the idle increases in speed. At first when i use it its fine, i take my finger of the throttle and it drops down in speed, But the more wood i cut the faster it will idle, until the point of when i take my finger off the throttle its almost running wide open. I dont think its anything sticking as it happens every time, and if i give the throttle a quick on and off it doesn't make any difference. Once it cools down it runs fine again until it gets hot.