2004 250 fourtrax starts up nice then after about a minute the idle starts to climb up if I flick the throttle a couple of times the idle comes back down but starts to climb back up after a minute or so again . I have taken the carb apart and cleaned and recleaned, checked the valves. I have run out of ideas it is becoming a pain , sometimes I can't get it into reverse or neutral because it won't rev down even if I flick the throttle