I agree with the last set of replies as well...I went through FOUR alternators in a week!!! (AutoZone/Oreilly's).
Some Word Of Advice is to buy a brand new alt. from Ford since you get the dealer hook up....99.99 percent sure that one of the brushes in the regulator has broken or been sheared off...Not A big deal But Get it fixed soon and dont drive her unless you have to..(youll lose the battery as well)

CSVT E0 3L 14.5 @ 94mph, Stock Intake, Stock Exhaust minus Resonator, CEL, And Broken Pass. Side CV...Untuned.