Do your own diligence on the hundreds of posts here about this problem but I would ask you to consider a few questions.
1. Ford says the hesitation/stumbling problem is normal, why then does Consumer reports include it as a bad thing in its reviews?
2. Many other brands have this transmission, do they all have a similar problem? (my VW GTI did not)
3. when cold weather hit new england, 2/3 of my problem went away. If it is normal, why did it go away ?
If you like everything else about the car, like I do, you need to be tactfully persistent about this issue. Don't just take the party line from the dealer and go home. be willing to contact the Ford home office customer service.
And do your homework, once you have read the hundreds of other posts and if you have ever owned another brand like the VW GTI-same type transmission, then you are better equipped to continue seeking a resolution.