While driving my F350 the check engine light.

While driving my F350 the check engine light comes on when I brake, the truck will not respond when I press down on foot pedal. The engine continues to run but will not rev up, It acts as if the foot pedal is not connected. It only last a second, Once I press down on the foot pedal & release the Check Engine Light goes off on the Truck operates fine. I have had it in the shop to replaced all injectors and replace a leaking fuel drain valve, but the problem still exists.