Unfortunately my friend, it doesn't work like that. Tuners can only be used on one specific vehicle, and if you were to purchase a tuner it would identify your current setup as "stock" and any changes from that would be considered a "tune" The only way your car can be set back to factory is with the original tuner used to program it (assuming that tuner was first used when the tune was in fact stock) or by having it done at a Ford dealer. Good luck to you.