I owned 2 Excursion before my current combo. Excursion make great tow vehicles however they can be finicky due to their soft rear suspensions.
Air bags,sway bars ans RAS (Roadmaster Active Suspension) are all popular fixes.
I also believe you need to upgrade your hitch. The push pull effect can be eliminated with a premium hitch. A Hensley or Propride hitch will deliver an entirely different/rock solid tow experience.
I was not satisfied with my Excursion TT combo until I upgraded to a HA.
Photo of my old rig with Hensley. It was an awesome combo