I installed a new chinese carb on my 1072 cub cadet 108,,Thottle lever set at 1/2 way,move lever 1/4 inch up,tractor starts no choke and runs fast(not full speed) return lever to 1/2 way and engine idles,go down past 1/2 way(1/4inch) engine stalls,,,,should i leave it alone or do i adjust the carb so i use the full range of the throttle lever and the choke to start,,,,,i think now i'm running rich