My 2000 Venture has been consistently giving what feels like a hard shift at 40mph,45mpf and 50mph. I read that other people were having the same problem, but there's weren't consistent. My van does it everytime I reach those speeds, and it is pretty hard jerk.

My 2000 Venture has been consistently giving what feels like a hard shift at 40mph,45mpf and 50mph. I read that other people were having the same problem, but there's weren't consistent. My van does it everytime I reach those speeds, and it is pretty hard jerk.
check the speed sensor