I have the exact same issue. I believe the problem lies within the torque converter, but have not found a solution. Car has been to two dealerships and been driven by several mechanics. None are willing to help because they are not certain what is causing the issue and it's mild.
Major problem for me is, once I tune with with any of my SCT based tunes, the stutter/jerk spreads like wildfire to include all gears and speeds up to about 2,800 rpm. With any tune, once under load, the same stutter/jerk becomes unbearable.
Curious question...do you live in a hilly/mountain area? I do which makes the problem significantly worse.
My advice to you is make sure that you either get the problem resolved or don't waste your money on an SCT based tune. It will make the problem MUCH worse.
Edited to add...if you search here and on shoforum you will find others with the same issue. So far, all reports have been from non-PP cars and it centers around 1400-1500 rpm in 6th gear. That is if untuned. Once tuned it spreads. No one has posted a fix except one person that found a Livernois tune to solve his issue. Not sure it his was the same problem though.