error code 7 is accelerator input voltage too high when key is first turned on

error code 91 is pump motor temp too high

first i would check the accelerator pedal sensor and make sure its returning completely when released.

as for the pump temp problem, verify the temp of the motor, use a temp gun
does this truck have any attachments on it? any sort of clamp?
generally if the temp sensor is bad it generates a code 43, since you didn't mention this code we can assume the motor is actually overheating for some reason.