This type of problem could be caused by either the throttle or controller.
What we recommend to do is unplug the throttle from the controller and see if the motor still runs then. If the motor still runs with the throttle unplugged from the controller then the controller is the part causing the problem. However if the motor stops running with the throttle unplugged from the controller then that points towards the throttle being the faulty part.
Please let us know how it goes.