Check all that has been suggested to make sure you don't have any suspension problems causing it to be worse than is normal. Repair any faulty parts and if that doesn't help adequately, you may have to consider the same thing I did....a Class A Motorhome doesn't drive like a car, or even a passenger truck. It took me a while to get the idea through my head that it wasn't going to be sucked into the side of a tractor-trailer every time one passed me. I remember growing up traveling, my Dad pulling our tag-along camper, and every time a truck passed us he would remark how much it pulled him. He finally talked to a truck driver who said that he just needed to relax, not panic and over correct and the pull would be gone without any harm. I panicked at first when I started driving our Class A, but thought about the advice given to Pop and now, I just drive through it. In all honesty, I find that some smaller cars make more impact when passing than the big rigs.
In summary... check tire pressures, for repairable items with your suspension, consider add-ons like track bars or air bags, and other than that, go drive your RV and enjoy camping!
1999 Holiday Rambler Endeavor, 36' Gasser
Triton V10, Ford F53 Chassis
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