i have a 92 caravan when you tke off it shifts untill you get to 30 mph then down shifts to low and wont shift unless you shut the motor off then it starts all over

Sounds like it's going into "limp mode" meaning it won't shift higher than second gear. This happens when the transmission computer detects a fault that will damage the tranny if not fixed. Head to a shop so they can connect a specified transmission scanner and read the tranny codes. Don't like shops? If you haven't lately change the fluid and filter. Next I would change the input and output speed sensors.

First I should ask which transmission do you have? Any other symptoms no matter how unrelated you may think they are? Seeing a check engine light?

i changed the filter and fluid all the sensors had the codes checked it was clear but still wont shift