My Hyundai is giving me a major headache. I bought a 2009 sonata used a few months back. Not long after I got it, I was having issues with it jerking around 20 mph. Sometimes, it would have a few issues with it jerking some when I was taking off. This was only right after the car was started. I took it to a local Aamco. The guy told me that it was a 2-1 downshift pump. He "relearned" the transmission and the problem went away. Now, it is back. At the time, he did some research and thought it may stem from a calibration update they had issued. He didn't have the Hyundai software to try that fix. Does anyone know what he was talking about or have any experience with the update? Does it fix the problem for good?