I am experiencing a chugging from the transmission on my 2010 V6 FWD when driving from about 15-25 mph (parking lots, residential streets, etc). To me, it seems as if it doesn't know if it wants to be in 3rd gear or 4th gear (or 4th & 5th), so it goes back and forth between the two gears until the speed is increased. Similar sensation when driving a manual shift in 4th gear at really slow speeds because the RPMs are too low.
I happened to mention it to my sales person yesterday because I had to pick up my license plate, and they said that Mr. So-n-so, (pointing to a customer in the showroom) mentioned the same thing.
Definitely doesn't feel like a mechanical problem, but more than likely a software problem. I will make an appointment soon to get it taken care of. Hopefully.
I will let everyone know of the outcome.