I agree that Ford should take that defective vehicle back. I certainly wouldn't drive it anymore, I value my and others lives. Also I wouldn't take a similar vehicle as a loaner or in trade, since I believe you said you experienced this problem with other Freestars.
From your experiences it appears Ford has a huge problem with this vehicle and have yet to come up with a fix. I've experienced this run around with less serious problems.
Why not go to the media with your problem, if Ford won't take it back. Tell Ford before you do what you intend. Be clear, firm, and document clearly all communications with Ford.
Another option that would fix your problem quickly with the least hassle would be to just trade the dam unsafe piece of junk on a Chrysler or Toyota.