While driving will a high whinning sound shortly followed by a banging
sound as the transmission changes gears.
Then proceeds into a herky-jerky motion if you continue to keep driving.
If you stop the car and turn off the engine for a few minutes and restart
then the van will run fine for awhile.
Had the same problem with a Pontaic Transport. In both cases the
mechanics could not find the problem.
Any help would be greatly appreciated.