My parents recently bought a 97 Town and Country automatic with 3.8L V6. The previous owner had the ATX fluid and filter changed, and it shifts very smooth. Most of the time it shifts through all gears, including overdrive, but sometimes it won't enter overdrive. There is no rough engagement when it works, and when it doesn't work it is almost as if the gear selector was left in 3rd position - it shifts to
3rd and won't go any higher. The only way to correct it seems to be to stop the vehicle, put in park, and restart it. After that it works fine. Any idea what the problem could be? Check engine light is not on.
Thanks.