I called my old buddy Red about the forklift and he said he had a similar problem with a model like this. He said to check the brushes in the motor...
I dug down to the motor, took it apart, and what do you know? This motor is brushless. :) Everything in the motor looks right.

I also rechecked the "go" pedal potentiometer with some better knowledge, and it's working as it should.

I also hooked the battery pack from our Toyota up to this truck and there was zero change. Just to eliminate a battery problem.

So I have a new theory now: No codes thrown.... I know on our Toyota forklift we can set the max speed, max lift rate, etc. Maybe somebody set this forklift to a max speed of.01 mph? If I could figure out the password to it, maybe I could check that setting (if it has it). That would be a super simple fix.

-Kevin