2004 Hyundai XG350 Sputtering or not "taking" gas

My husaband and I just got back from a 3 day trip of about 700 miles round trip mostly highway driving some in HEAVY traffic. On the way home after 1-2 hours of horrible stop and start traffic the car seemed to not "take" the gas when you push the accelerator. It did this about twice the second time it stopped running and we were able to pull into a parking lot. He couldn't determine anything and we started going again. We stopped at an advance auto parts because the check engine light came on. He said it had some code that meant the emissions needed to be checked. We are at a loss as to what might need repair, fule pump, sensor where should we start?