We have a 07 Expedition that we tow our 20' aluminum v nose trailer (4500lbs loaded) with. On a two lane road its fine, but when I hit the highway, lookout. It has the independent rear suspension which rides great, but for towing the trailer its a real ride. It seems to do a lot of "hunting" when getting passed by a mini van. I have check with several shops to see about springs, airbags or anything that will help the hunting problem. Has anyone ever had this trouble and fixed the problem or what can I do? I keep telling the wife I need a new truck, just not getting to far.