Unless the injection pump generates somewhere around 32-3400 rail psi then the injectors will not fire. When you shoot it with ether it spins the motor over faster creating more rail presaure which enables the ECM to fire the injector solenoids. When the motor is warm or outside temps are warm the oil is thinner so the motor naturally spins just a bit faster which can cause it to start warm and not cold. Either the batteries are weak and its cranking too slow or most likely you have 1 or more injectors bypassing fuel.