Shocks or sway bars

It is your sway bars, if your bushing are in good shape, try moving the end links to the inside holes and see if this helps. Its call the CHF (cheap handling fix).

Start by checking the sway bar end link bushings. Many came with 8 rubber bushings. A little play in each renders the sway bar ineffective. If worn/you can see any light above or below a bushing, strongly recommend replacing with polyurethane bushings.

And, certainly on a 10 year old unit, check the shocks.

SoCalDesertRider wrote:
Shocks might be worn out. Replace with heaviest duty shocks you can find.

Adding or upgrading to heavy duty sway bars, front and rear, with stiff polyurethane bushings will help alot, once the shocks are good.

Upgrading to heavier duty rear springs, heaviest available, will help alot too.

X-2, on the worn out shocks! I own a 04 Winnebago and I had the same problem. My RV came with Monroe Shocks off the showroom floor and they didn't last very long. I upgraded to a better shock and that cured the problem. Please note that Winnebago changes there chassis every four years. I have a 04 Winnebago on a 03 chassis so I had to buy shocks for a 03.

Shocks might be worn out. Replace with heaviest duty shocks you can find.

Adding or upgrading to heavy duty sway bars, front and rear, with stiff polyurethane bushings will help alot, once the shocks are good.

Upgrading to heavier duty rear springs, heaviest available, will help alot too.