WARNING: This page is about a different car, the 2013 Lincoln MKX and 2013 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.
Inspect the flexplate for:
Any cracks.
Worn ring gear teeth.
Chipped or cracked ring gear teeth.
Fig 1: Inspecting Flexplate For Cracks, Worn Ring Gear Teeth And Chipped Or Cracked Ring Gear Teeth