Prentice; Test the accelerator pedal transmitter under normal and slow operational conditions by a disconnecting the L25 plug from it's socket and apply 10v to the plug's 1 and 3 pins. Look for the pin numbers of the back side of the plug.
Voltage across connections 1 and 2 should read 4.5V dc with the pedal in neutral position. With the pedal actuated the voltage across 1 and 2 pins should be 4.5v to 10v. Rising and falling uniformly and if not within specification replace the transmitter.

Is it an electrical or mechanical issue? Does the drive motor continue to spin, but doesn't transfer power to the wheels or does the drive motor stop?