1998 Bombardier CLASS-E NEV stalls

I have a 1998 Bombardier NEV Class-E that shuts off when putting it in "D" drive mode, the p/I indicator comes on and it stalls. It also appears to shutoff when I have it in "G" mode when I exceed 18mph or when I try wipers, etc... Lights arent working and I just replaced all batteries, master cylinder to get it running and brakes to work. I still need wheel cylinders but I am concerned with the stalling. Any ideas? This is my elderly Father's and I am trying to get it running so I can sell it and he can sure use the money.

:cry: