I'm not sure what they mean by "air box", under your description, but let them try. If it doesn't work, take it back. Let them fix something else, and try again. If anything works, then you will have a good truck, only suffering some inconvenience (which they should compensate you for).

In the meanwhile (on the QT), look into your state's lemon law requirements. Some states require a specific number of attempts to correct a defect over a specific period of time, then the manufacturer is required to buy back or replace your vehicle. If you use your vehicle in accordance with the manufacurer's specifications, and it overheats, it is not performing as advertised (what you paid for), and is defective. Do not mention the "lemon law" to your dealer until they have met all the criteria. It will only create friction. The best option is to keep the dealer "working" for you. Try to be polite, but don't bend over for them.

Good luck!