Towing Issues: 05 Excursion sway, freeway speeds, tows

Question
I have a 05 lifted Excursion. I purchased a 28.6 32' overall Rampage toybox. The trailer weighs 11.4K loaded we usally tow light, at 9,800 or 10,000lbs.At freeway speeds we get a wip side to side,when passed by bigrigs or going up and down through the summit.I have 2 sway controls weight distrabution hitch.I have adjusted w/distra. chains and my load. I have scared my wife and friends HELP!! I have the trailer set up 1" lower in frt than the rear.Is there anything I can do,or do I need a new truck. the trailer tows great behind my brothers lifted F250 and friends dully.Thank you any thoughts will be greatly appreciated.

Answer
As much as I would love to help you with the question, I am going to suggest that you check with the other expert when he comes back off vacation from here...

I got an idea or to but since it is not my area of expertise, I am going to pass on this one..  


Sorry for not being able to answer this question.