My sled was running perfect then it will fire up run prefect at an idle but die as soon as you give steady throttle if you pump the throttle it will rev up and as long as you keep pumping the throttle you can get it going and keep it running, but as soon as you try to run the throttle smooth it dies. I've drained the fuel, cleaned the exaust valves, changed plugs, replaced fuel filter, and still no luck any suggestions would be greatly appreciated!