no impulse at fuel injectors?

i have a 96 taurus with the durutec engine, the problem is it will start and run fine for about 2-3 seconds and cuts off? i replaced the following parts( fuel pump, fuel regulator, fuel filter , crank sensor, cam sensor) i took the car to a mechanic found out the injectors wasnt getting impulse. iam thinking the mass air flow good be bad and causing this problem. does anybody have any ideas, i sure could used them, thanks for reading this.

i had help at the taurus forum with two replies, the one that lead me to the problem told me that the anti theft system would cause this problem, i notice every time i started it the theft light would blink, i was using my spare key hidden under the car after i replaced the fuel pump, then thats when the problem started, the spare key was not coded to start my car, put the other key in and started right up, car runs like new now!!!!!! 140,000k going strong ,thanks evervy one