Sicko- I've had this problem before in the past and i thought it was gone but obviously not. The dash/ECU is losing power somehow. A little logo comes up on the dash showing ECU and a unplugged symbol and it just kills the motor and fuel pump. From my understanding its either a loose wire/plug on the dash (which i jiggled to get it working again) or some oxidation on the protection relay near the battery. Im going to check it tomorrow but i've been told what is most likely the cause so hopefully its a simple fix.