I've read about some of the 5 speeds downshifting woe's several month's ago. When my '12 3.6 Limited (10,400 miles) is coasting to a stop, I can feel it downshift at an appropriate speed and the engine rev very slightly, but it's not enough to bother me and it certainly doesn't 'clunk'. On brisk acceleration, the tranny is very smooth. Concerning the lane change behavior, are your tires properly inflated?