I had exactly the very same experience. Originally ran a set of Toyos and they were fine and after they wore out, bought another set. They were all over the road immediately and I went back to the dealer and they installed a more expensive steel belted radial Toyo tire and they too wandered all over the road.
Finally, out of total exasperation, I bought a set of Michelin XPS steel belted radials and they run PERFECT.
Many people will swear that the Toyos are the only tires to have but I know what I know and I don't have time to be chasing the "right tires". I know what works and what doesn't.
On a side note, I was told that tires, when new, need time to break in and once they are, will not be squirrely.And yes, my rv already had newer Bilstein shocks and Helwig sway bars.