no response from accelerator when pushed down intermitently

Bought a new car so I would not have to worry about breaking down. Dealership (Ford) talked me into changing to a Mazda at their dealership next door. This is my first and last Mazda product. Within 2 months it has left my wife stranded and nearly killed me. The problem is that the accelerator doesn't respond when pushed, intermittently. I have taken it back to the dealer, first they said they couldn't duplicate the problem and had no other complaints, then said there was a TSB concerning the issue. They took out my computer and sent it off to be reprogramed. I got the car back and it was fine for about 3 weeks. While out of town I had to get out of a bad spot in traffic fast, pushed the accelerator to the floor and nothing. I almost got creamed. It was really scary. I called the dealer to report what happened and was told that if I couldn't duplicate the problem with one of their techs there was nothing they could do. It continued to have a flat spot at full throttle for about a half a day. By the time I got home it wasn't doing it anymore. Now I'm afraid to drive a car I'm paying $415.00 a month for. I am going to try to reach out to Mazda corporate and ask for help in getting this resolved.