engine goes dead after about 3or4 minutes it is smokeing good an then the smoke stops an starts to loose power bad i can idle it down for a minute or two an then it will back run good for a few more minutes i have changed glow plugs set main needle at 2 to 3turns out an the low speed allway in it seems to run best at this setting motor does not seem to be runing to hot a have changed all fuel line took muffler off an resealed it runing 10% fuel thanks for help