Was in the same place when we got our MH-If I looked away from the road no telling were it was headed when I looked back it was a bear to drive.Took it to a Freightliner BODY SHOP where they did a four wheel alignment check. There was some out of alinement with the front wheels but the rear wheel were cut loose from the frame and re aligned and welded back in place. Drives like BMW and has since Sept 2006. It was done under warranty by Freightliner.
My Coach is now 8 years old and took it back to the same shop after new tires were installed and no adjustment was needed. So may be that you need all four wheels checked by a shop that can perform the alignment that may be needed.
Jroan