WHat did you put in as replacements?
I only ask because most of the aftermarket brand COPs have a much shorter life than the Motorcrafts. About the closest store-brand I've used is NAPA Echlin but those cost nearly double the Motorcrafts!
Also, check all you fuel injector connectors. Its VERY easy to break off the retaining tab when changing the adjacent coil. I've broken all of mine, so now my injector connectors are all zip-tied to the injector. One backed off once on a drive from Whistler, Never threw a code but made the idle less smooth, and the emissions were were pretty smelly. Ran fine while driving though.
