Transmission does not want to shift up, stays in low. reverse and neutral fine.

its freeeeeeeeeeeeeee

seek to diagnose it like AAMCO transmission

It's likely a speed solenoid. They generally go bad from normal use over 20 years. You should replace all of them at once. There are 3. They are simple to get to under the van and easy to replace. The connectors may be bad as well. The whole process for solenoids and connectors shouldn't ve blmuch more than 150-200$