I have a Club Car 2006 DS 48 volt that is new to me that's shutting off while driving. While driving it will shut off as soon as there is no load on the motor. Like if I go downhill or the down side of a speed bump. I have to completely let off the go pedal and then press it all the way down to get it to go again. Going uphill or on flat ground at full speed it's fine. When it shuts off it feels like the brakes are being applied. Sometimes even locking up the rear tires if on loose enough gravel. Any ideas?? Thanks in advance.