I have a late '90s Voyager on which the transmission sometimes does not engage. This happens shortly after starting and always just as one slows down for a junction and then tries to accelerate again to speed up. The engine spins quickly, but the transmission does not engage, so no power is transmitted and the vehicle does not accelerate. After a couple of times of releasing and depressing the accelerator pedal, the transmission will smoothly engage and the vehicle will proceed normally.
Does anyone have any suggestions on what might be happening?
The transmission has about 50k miles on it since a rebuild at 95k miles. I have been careful to change the transmission fluid every 15k miles since the rebuild, using approved fluid (although I have moved to the semi-synthetic fluid now, which is claimed to be compatible with this transmission).