Sangone, I had the exact problem as you; doors restrained but shuffling back & forth behind the strap.
I cut out two pieces of medium density foam, both about 1-1/2" thick by 3" x 3". Then glued them to gether with contact cement (like Pliobond) making a foam cube about 3" x 3" x 3". Then I used the same glue and stuck the foam up on the coach wall, just under the door slide rail. Now the foam holds the doors in 'tension' and they don't bump going down the highway.
(At first I thought "this'll look ugly", but I used some charcoal colored foam and being located up by the top corner of the doors, you really have to look to find it).
Last Brave 2004 34D