Automatic Transmission problems of the 2008 Kia Motor Sorento

My 2008 kia Sorento is experiencing intermittent transmission lunging. There is only 40,000 miles on this vehicle. The vehicle does this every day, except when I take it into the dealer. Once I do take it in to the dealer, they say that nothing is wrong and that they cannot get the car to do the same thing I do. I believe that no diagnostics were performed, and I know that a proper road test was not performed. I have taken this vehicle in 2 times within the last month and no solution has been determined.

Transmission - vehicle turns on, when placed in reverse a loud/hard jolt occurs. When placed in drive, vehicle will hardly move without pressing all the way down on the gas pedal. Engine roars and hardly moves forward. Happened on two occasions in the last few months. Was recently fixed two months ago but happened again.

The contact owns a 2008 kia sorrento. The vehicle exhibited abnormal hesitation when accelerating from a complete stop and would only accelerate at a very low speed. After shutting the vehicle off and allowing it to sit for a few hours, the vehicle would operate as normal. The vehicle was taken to an authorized dealer where upgrades were made to the computer system. The failure since recurred approximately 3 times. The vehicle was not taken back to the dealer for further repairs or diagnosis. The failure mileage was 20,000 and the current mileage was 25,000.