I am arriving in JFK from Frankfurt at 10:45 AM. I have a 6:30 PM flight out of PHL. For those who know these places, does this seem reasonable?

Any recommendations on the best way to shuttle between the airports. Is there some company that runs shuttles directly between JFK and PHL?

I am thinking about renting a car, however it will be on a Thursday and I am wondering if it is reasonable to try and drive myself during those hours between these airports. I don't know the area.

Any advice would be appreciated because this is the biggest uncertainty in my travel plans.