My 2012 F-150 XLT with a 3.7 L V6 option has a strange sound/acceleration hesitation issue. It has been doing it since I bought it, that I can remember at least (currently 10,500 or so miles and bought brand new); I first thought it was just the engine that wasn't powerful enough, but have now realized it only occurs sometimes. When this issue isn't occurring, the truck changes gears and accelerates smoothly. However, when I have been driving for a long time, the weather is too hot, and/or it is windy outside, I have realized it starts not only hesitating under acceleration (if I depress the pedal more, you can even feel the truck slightly shake a little and accelerate even less), but also making a different sound, almost as if the engine were trying harder (although accelerating less). If I press the pedal enough to make the truck downshift, the sound still occurs, but the acceleration gets slightly better. Also, I have realized that when I need to pass and the truck is having this issue, that if I press the accelerator sufficiently, it'll hesitate, but then all of a sudden just suddenly surge upwards to high RPM's (all while making the different sound). I hope I have explained myself clearly. I attached a link to a video, and you can hear the different sound/hesitation at 0:31, 0:41, and 0:50 (the video contains a portion which shows the truck accelerating normally for comparison purposes). Thanks for any help. I don't know much about cars, but I hope I can get some responses so I can explain to my dealer what the issue is because I'm at a loss as to how to even explain this.
Video: https://www.dropbox.com/s/ktly64zlm7...celeration.mov

 

You can take the mechanic on a ride and show him the issue. If it doesn't happen on the drive then show them the video.

 

Yeah I think the video is a better idea, as this hesitation issue only occurs after driving it around for a while (some days it happens faster than others, other days I don't even notice it happening).

 

For anyone with a similar problem, it turned out to be a problem with the mass air flow sensor. I just got it fixed, and after driving it for just a while, it seems much more responsive than before (and never did the strange sound/hesitation as seen in the video).