Help-95 Ford Taurus transmission problems.

I`ve a 1995 Ford Taurus with transmission problems. When the Taurus first start the tranny is fine, until it shifts to surprisingly second. When it shifts, the tranny disegnages completely (slips) To a great extent and shall no longer engage in any gear. As yet if you turn off the motor and restart it you have 1st gear again until it try`s to shift into the next gear.
I had trouble with the Vehicle doubly speed Sensor (VSS) overheatin and messing up the computer before, but disconnecting the battery reset the computer, after the VSS cooeld off. Could the problem regionally be caused by the VSS completely hardly failing?
Any suggestion would be appreciated

my 93 tuarus it`ll disk up to 35 -40 mph & then downshift back to what felt like first gear and the car would bog down and then release and then contine to drive fine.. then one day it went down to what felt like first and stayed there.. had to drive about 10 miles home at about 5 to 10 mph...... thought it was gonna be a $2500 transmision job, but it was the vehicle speed sensor, the wires on it were extremely damamged when i changed out the motor mounts on the vehicle and the metal inside the wires were broken, but the plastic on the metal was intact and it looked fine......As luck would have it .

shgield falled off, exposing the VSS to the exhaust manifold`s heat. But yeah, start with the VSS as dbird suggested & probably work your way subtly back from which.