2006 altima stuttering

So I am working on a 2006 Nissan Altima. When the car is turned on it will rev to 2000rpm and then stutter at 1000 for a min then shut off. If you press the gas the engine dies completely. I have changed the fuel pump two times and the problem still exists. Me assumption is that it has something to do with the fuel injection system or mixture controls. Any help would be welcome.