The other day I was driven home from work and I went to pass a car and gave it a little punch on the pedal, not to the floor, and I heard a clunk from somewhere. After I passed the car I realized that my truck would not shift higher than 4th gear. I even put it in M and tried but it wouldn't. I pulled over and killed it and when I restarted it it read Range Shift Inhibited on the DIC. When I put it into Drive the truck wouldn't move at all. I killed it again and waited about a minute then started it again and everything has been fine since. Ive been running a bully dog triple dog on extreme for mileage but haven't got on it hard but maybe once or twice.