Well the flex plate was definitely bad. 4 sections at 90 degree spacing had teeth that were half gone. No teeth were completely gone but most had half of the tooth ground away.

Turns out that my stater was also a problem although it looked and seemed to work fine. Replaced it with a Motorcraft reman and now it cranks every time.

Upon close inspection the gear on the old starter was cut just a little different then the motorcraft. I'm assuming this effects the engagement. The moral of that story is a motorcraft reman is better than a new chinese starter and well worth the $50.oo more.