hope some one can shed some light on a problem im having with my 853 bobcat. while running my machine, the throttle was 1/2 way up and the engine idled down to idle speed , the throttle was still at 1/2 at the lever , i idled the throttle down to idle,then moved the throttle back up and it revs like normal , it ran normal for about 5 min. then idled back down on its own again. i replaced the fuel filter ,that didnt help. any help would be great