2001 Gem e825 Stall

Hello. I recently purchased a 2001 e825 with about 1380 miles. The batteries are 12-18 months old and it has a 5HP motor. At top speed, the speedometer shows about 27 MPH.

The problem: At top speed, with the pedal buried, the car seems to stall. It chugs and slows down; when I lift my foot off of the pedal it gets back up and goes until it hits that top speed again. There is an error code that flashes when this occurs, but it flashes so quickly I can’t see what it is.

Any ideas on what this could be?

Thanks!!!

That’s the speed-limiter switching the motor to a generator for regenerative braking. Stock programming is too aggressive in my opinion for regenerative braking. When I reprogrammed my 2002 controller I reduced the regen armature current to 100 amps max and set the cut-in point to 35 MPH. Much better now on downhills.