Take the access cover to the flex plate bolts on the bottom of the car and have a look at the ring gear. Check for rounded or missing teeth, if everything looks fine I would have the starter replaced so as not to damage the flywheel if it is hanging up on the teeth when you crank. There is a revised flex plate at the dealer, as I had to replace mine as sections of teeth in several spots were all but gone. Check it out from the bottom of the car...before you do more damage.
