Simple tips and things to check.
Pull the transmission measuring stick, look at the color of the fluid, it should be a reddish color, not brown. Original fluid is red, it will discolor with age, if it’s brown and has a burnt smell, it means the transmission has been slipping, the internal clutches are worn.
If there is no burnt smell or brown fluid, it may just be a simple transmission reprograming or updated downloads to the ECU (engine control unit).
Modern automatic transmissions are controlled by the ECU. The ECU has the ability to memorize your driving habits, how fast you accelerate, average speed, distance travelled, etc. This is to optimize fuel economy and develop shifting points. If another driver uses the vehicle, it can change the shifting points, because of different driving habits.
Transmission fluid should be changed regularly, each manufacture has it’s own recommended change intervals. Some auto dealers recommend a power flush when you change fluid. This has some value, since torque converters hold over half of the fluid, and it can’t be drained manually.
James Collins Ford