Ok y'all, have a question, wanting to see if anyone else has had this issue and how to fix it.

Truck is a 2017 F350, 4x4, Dually. Has 5,400 miles on it. From the beginning, only when pulling a trailer, it will intermittently buck in 3rd, 4th, or 5th gear, sometimes all 3. When I say buck, what I mean is the buck motion a manual will make if you shift to soon, multiplied by 10,000. It doesn't throw any computer codes when it does it, and I kid you not, it will do it all the way to the dealership and as soon as they put the computer on it to monitor and make recordings, it quits. Most but not all of the time if it starts bucking you have to drop it into manual and override the gear(s). It doesn't matter how long you've been driving, it's acted squirrelly less than a mile out of the driveway, or not done it until I've been driving for 6+ hours. Ford has thrown their hands up after having it and my trailer for 2 weeks and it not doing it. They've witnessed it acting stupid so it's not in my head, there just wasn't a computer on it at the time.

Any thoughts?

 

What engine?

 

So are you saying that if you drop down a gear, sometimes it stops and sometimes it doesn't OR sometimes it clears up on its own without dropping a gear?

if you have a diesel, try searching for "jackhammer valves" and see if that's similar to what you are experiencing. There are videos of it around and it seems to sound a lot like the very heavy lugging sound you describe.

If it only happens during a regen, that could explain the intermittent nature of the problem.