I was having the same hesitation issues between 2700 - 3000 rpm. At one point I got an oxygen out of range code and was told by the dealer that the stock ECU programming has too narrow of a range of values and the ECU will cut power to keep the emissions in check. The O2 sensor itself checked out OK. I didn't want to pay the money to reprogram the ECU to the updated software so I lived with the hesitation issue for 6 months. Finally yesterday I took the car in and had them update the ECU programming and the problem with the hesitation was solved.