2016 6.7 jerking and chucking in 4th and 5th....

Just bought the Truck last September and was very smooth in all ways until in December when I re-tuned with EFI plus trany tune and at same time installed the 2 micron "Cat" fuel filter.
I sensed a pulsing right away which is tolerable running alone.
However when towing it becomes far more apparent/exaggerated and very uncomfortable especially when towing in the mountains because up every grade it creates chucking all the way.
With the initial EFI tune it did not do this when towing.

Like I said our first two months of experience was great. My installer has scanned while towing and finds nothing amiss.
Other than the retune the only difference compared to September is much colder weather.

We are at a loss as to why this is happening. HELP?

Interesting user name.. First post even.

Your tuner/shop that has helped you get setup will need to also be the ones to help diagnose the issue with actual tools and data. Guessing is futile.

He has done that. Can't find a cause!

Admitting that I've been conned a few times in my life keeps me humble and sceptical.

I am experiencing a similar issue. Did you ever figure it out? What did you check?

Who's tunes?

I went back to the dealer that had installed the original tune. Told them what I had done and the resulting chucking. They were not at all surprised and said they had seen this before. They suggested it had something to do with turbo tables. My driving experience tells me this is the case as I could make the chucking come and go with slight preasure on the skinny pedal.
They removed the new tune and reinstalled the original. Chucking is gone. I pulled trailer lots and there is no chucking. There is something about the engine side of that tune that is not compatible with my truck I believe even though the same tune might be fine it other trucks.

In light of the original tuner saying they "had seen this before" this may be an issue that some one needs to address.