Texas - DFW for 7hrs

I have a flight connection in DFW on the 12th arrive at 12.35pm and leave at 7.45pm both flights are international.
What do I have time to do? (renting a car is not an option).
Do people still try to talk their way onto the shuttle to go to the CR Smith museum?
Is it worth it to go to the JFK memorial?
Thanks for the help :)

You could ride the Trinity Rail Express to either downtown Dallas or Downtown Ft Worth, and have about 3-4 hours to enjoy. Both have a variety of attractions, but I hesitate to recommend spending an August afternoon walking around downtown, as temps will be around 100, and it may feel much worse than that...

Personally, given a connection between two international (long) flights, I'd investigate a 1 day membership in the Admiral's Club and simplx relax. Not knowing your citizenship/immigation status, the hour or so spent clearing Immigration and that you may have to deal with baggage and a trip through security will cut your 7 hours down. Add the "early at the gate' requirement for your connection, and a big chunk of clock will be eaten away.