Taken all the steps to prevent sway. Still swaying. Help!

I flipped my axles on a 27ft Fleetwood and towed with a 2500 suburban and a reese 12,000 pound dual cam wd hitch. Never an issue.

I suspect a better wd hitch as you do not say what you have, as well as check the tongue weight. You may also have loaded the trailer nose heavy which would result in a light rear. When setting up the wd hitch you should be as level as possible. You could also be tail heavy, so ivestigate how you have loaded your TT. Reset the hitch and go for test rides.