I am having a problem with my car but only at night time. After I have driven my car for about 15 minutes at night when I stop at a stop light my car will die on me. I can get it to start but I have to pump the accelerator and keep it going. If I drive it at night and go to the store when I get back in and turn it on it starts but I have to pump the accelerator to keep it going. During the day I have no problems with the vehicle. It also died on me once when I turned my a/c on which I rarely do. People have told me it may be two different things either the fuel pump or the alternator. What do you think it might be?