I drive a 09 Focus SES with an auto. A couple months ago I noticed that it sort of bumps along in 4th gear around 40-45mph. It feels as though someone is pushing the car in short burst and the car has a hard time accelerating until it downshifts. I thought not much of it until I was riding in the passenger seat when it did this and it makes a clunking noise along with these bumps. It does it every single time around 40-45 if I try to lightly accelerate the car. I have a two year unlimited miles power train warranty, so would this fall under it? Is my 4th gear band bad? Do you think they will fix it or give me a new car that's valued the same of the lot?