2001 Elantra-bucking and hesitating

I am hoping you can help me. I purchased a 2001 Hyundai Elandra GLS, Auto in 2001. In 2003, the car started to hesitate when accelerating and the gears were not shifting properly (they slam into gear). After this would happen, the check engine light would go on. I would take the car into the Hyundai dealership that I brought it from and they would hook it up to the computer; the following two codes have been reported: P1529 and P0720. I believe code P0720 has to do with the Output Speed Sensor because they have replaced it 5 times now in the last 3 years. The car has just over 30,000 and I usually use it to run errands around town (very local). I noticed that the car typically will hesitate/buck and then shift into gear hard after I have ran a few errands and the car is hot (a hot start). I have taken the car to the dealership 9 times in the last 3 years and the compliant is always the same; the car is hesitating and bucking on acceleration and it is not shifting properly. I am hoping you may have an idea what the cause of this may be. I am starting to believe that there is something wrong that may cause the Output Speed Sensors to short and have no idea what would do it. The dealership said they have no idea but told me I could trade the car in. Thank you for taking the time to read about my problem. I appreciate any ideas you may have which would cause the hesitation/bucking and multiple sensors shorting out.