[BaconLover]

I don't know the answers to your other questions, but we just experienced something similar with towing our new TM as well. It was "porpoising" up and down and felt jerky. It turned out that the tongue was too high at the hitch and the back was low. Our Andersen WDH instructions specify that you want the trailer to be level, not slanted in anyway. Once we made the trailer more level and the hitch height lower, all of those problems went away.

You have to make sure your WDH is adjusted properly - that took some doing. My husband had to try different heights and take the WDH on and off, but he finally found the right combination that minimized up and down and sway. Pulls really nicely now! That WDH setup is like voodoo magic - sooo much to consider and mess around with! Good luck!