The truck is a 1999 f-350 5-speed. The truck has a bad stumble while driving in any gear, especialy below 2500 rpms. The stumble occurs sometimes at part throttle, but at WOT, the truck stumbles so bad it almost stalls out. The rpms dont move during this, no engine light, the truck has more power at part throttle than it does at WOT. It feels like it is starving for fuel. But the strange thing is that it doesnt do this all the time,one day it might stumble, then it will be a day or two before it does it again. Just wondering what might becausing this or if anybody else has had the same problem. Thanks for yalls time!!!