It sounds like you don't have enough weight on the front axle. On our Excursion when hooked up the front end is within 1/4 inch on when we are unloaded and we go down the road without any problem.
2011 jayco 33rlds, 2002 Ford excursion, v-10, 3:73 gears 4x4 mine. 2008 Suzuki sx-4, hers. Retired Air Force, now Retired.