2011 Coachman Freelander 21QB (3500 Express Chassie)

I seriously doubt if it is a problem with your trailer's suspension. More than likely, your tongue weight is too low. Typically, you need about 12 to 13 percent of the trailer's total weight on the tongue.

Also, do you have an integrated weight distribution/sway control device? Is it adjusted correctly?

Tires on the trailer and the tow vehicle can cause sway problem also.

You need to fill us in with more info.

Ron

PS...it's a Coachmen...not Coachman. Just saying ;)