Hitachi EX135UR-5 won't throttle up

I have a 2002 hitachi ex135ur-5 that won't throttle up. Worked fine then sat for a couple weeks and the problem started. The key will start the machine but has no effect from the on. It will only idle and they key will not shut it off. I have to use the manual emergency stop cable.
I have another identical machine that does run so I've been switching parts but no luck. I have checked all the fuses, switched relays around, changed the computer, the step motor, the alternator, the key...

Hitachi EX135UR-5 won't throttle up

Hitachi EX135UR-5 won't throttle up