Does it sound any different when you drive it? If you're saying you lost power, I am wondering if it's an O2 sensor that is jacked up and messing with your fuel tables. Could be starving the engine of power.
But yeah, definitely take it to the dealership...you paid too much to have to worry! And I wouldn't continue driving it until I go it figured out....or let Ford put it in writing that they told you to continue driving it...
2011 Mustang 3.7L, 6A, MCA Pkg, Ingot Silver w/ Stone
Perf Mods: FRPP 3.73 Gears, 87 Octane Performance Tune from BAMA, Airaid CAI, Magnaflow Comp Axle-backs
Ext Mods: Lower chrome billet grille, Tint
Upcoming Mods: Lowering springs