Need help

I have a 1990 Dodge B-250 9 . 04 trans. Trans rebuilt with new lock up torque converter . Having same problem with new rebuild as i had before rebuild Trans up shifts perfect . When coming to stop trans ( torque converter ) does not want to down shift . Remove one wire from sensor at back of trans . 3 speed works perfect but no lock up Has anyone had this problem . I even replaced the computer .