Given the fact you got your IS less than a month ago, I would beleive it is not one of the older ones made. The older ones or first ones made before Feb. (I beleive) had a slight hesitation while shifting between the lower gears. I forgot the exact gears. Then the TRAC ECU fix has to do with the Traction control holding on too long after it is needed. That might still be something you'll need depending on your VIN #. I suggest looking through some old posts. That is the best way to find out any info. you may not know or understand. Everyone who uses this website always sees the same questions being asked all the time, that's why I suggest you will want to use the search device. It'll save you some time.