Don't quote me on this, but air bags (like odometers) may have certain federal restrictions on them. Therefore, if you resell a car with a roll backed odometer or a knowingly faulty air bag, there could be legal implications. So search for any possible Recalls and then take it to a Ford dealer.
With that said, purchase the factory service manual from Helm, Inc.
http://www.helminc.com .
These are the same service manuals used by Ford factory trained technicians. If anything needs to be fixed, it WILL be in there.