Shifting is controlled by computer so a computer reset may help hard shifting. Might also want to check the fluid level and make sure it's good Mercon fluid. The atx will be in 'overdrive on' mode when the car is started normally. If you push the OD button it should disable OD and light up the dash light that means 'OD off'. A 1/2 quart of Lucas ATX treatment (Napa) in the tranny will smooth out the shifts but may only be a band aid over bigger problems.
