I did a search on this a few months ago and found that someone just replaced all of there 02 sensors and it fixed his problem. Which was the same code reading. I would say if you have all of the cats still on it will still pass emissions and if it doesn't bring it to Ford and make them fix it. With just one cat it will probably pass emissions anyways. Not sure if I would want some dealer changing my exhaust manifolds.
Green 2000 SVT #1166
mods-K&N open air filter & Custom heat shield, Custom y pipe and 30 in resonator,DMD, arm rest heightened
http://www.geocities.com/savinoss/Cars.html other cars-89 sable 197000 miles and still going-Wifes car 99 Mystique V6 5 spd