Bucking, jerking

When I accelerate up a hill or when I am traveling at 50 to 55 mph and accelerate slightly, my truck will bump or jerk a few times. At first I thought it was transmission, but it shifts smoothly and the tachometer doesn't move when it does it. There is no check engine light. Is it possibly a cylinder misfire? I thought that would cause a check engine light but maybe not. It will accelerate smoothly on a flat surface through all gears up to top speed. I also tried locking it in 1st gear and took it to 4500 rpms smoothly and the same in 2nd. It only jerks going up a hill or slightly accelerating on the highway from about 50 to 60 miles per hour.