[RedFiero]

The purple wire on the brake light switch runs the TCC (torque convertor clutch) and it appears that your TCC is staying engaged all the time.Thus running like a std trans 1:1 ratio. The TCC switch or sometimes it's called a Lock up switch may be bad too. Both of these are easy fixes, even tho the TCC Lock up switch is in the tranny it can be done w/o removal of the tranny. But if it's the Convertor it will have to come out. More than likely tho it's the brake ligt switch. When your driving at 50 mph , lightly touch the brake pedal, if you see a increase in the rpm's the lock out (TCC) is working if no increase Bad TCC or Brakelight switch. Remember its the purple wire off the B/L switch. Also of you have a volt meter hook it to the purple wire and if you see voltage through the wire when you touch the brake (at 50/55mph) then it is the Lock up switch. B/L switch 15 bucks..Lock up switch....30 +/- good luck just had the same problem and I almost went nuts trying to find the problem