2 questions hopefully someone can shed some light on... After I starte the max earlier, I turned on the headlights, and the engine shut off. What's the deal with that?

Also, I recently drove 700 miles through the Appalachian mountains with the max filled with clothes,tv, monitors and other crap, and the car definitely was jerky when i was going up the hills at 75-80, like it was loosing power. it only did this part of the time, and usually it happend right above 2000 rpm. is the car misfiring, or what? i guess i'll have to get it checked out, but wanted to hear some other opinions first.