Ugh,, not a really good way to get from JFK to PHL

I would largely agree with MisterNice and give 2 options

The cheaper way would be:
Take the subway train to Penn Station,
Train (Amtrak) to PHL's 30th Street Station,
then the local train (SEPTA, Route R1, located in the station) to the PHL airport.

Marginally more expensive and less trouble on your back would be:
Either taxi or express bus to Penn Station,
Train (Amtrak) to PHL's 30th Street Station,
then cab to the airport (~USD 15-20)

Gute Reise und Gute Gluck!