Your TCC (Torque Converter Clutch) is stuck in the ON position and not releasing when you step on the brake. It is like stopping an manual transmission car without stepping on the clutch. Pull the codes. I would suspect you will see P088 (E088) .... Torque converter clutch did not disengage when commanded OFF by PCM. The problem might be as simple as a disengage switch on the brake pedal, or as complicated as the TCC solenoid in the trans. A FSM would be a big help in diagnosing it (not Chiltons or Haynes). Ebay is your friend.