@salmonbum...
Edmunds has a long term review of a Jeep Rubicon. One of their monthly updates talks about the Jeep wandering on the highway and paved roads. Turns out the culprits were leaking/compromised shocks that they replaced under warranty. They drove the jeep down some pretty rough roads... I saw one of their videos where this road toasted the shocks on a Tacoma after 4 miles. What you've experiencing seems similar though more severe.
Are you saying the truck went from one dealership to another? Seems like a red flag to me.
I was reading a Jeep Rubicon long term review on Edmunds the other day. They had leaking/compromised shocks and as a result their Jeep was exhibiting similar behavior as your truck... maybe not as extreme. As you said, 370 miles and no one notices how your truck drives? No. Someone is not owning up to something. Plenty of stories of cars and trucks getting damaged on "test drives" at dealers and repair shops. I got a bad feeling someone decided to have some fun with your truck, blew out a shock or two, cleaned up the mess and passed the truck on to you without a word.