Check engine light

My 92 Geo Storm 1.4 L SOHC check engine light won"t stay on when I turn the ignition switch to on. All the rest of the instrument panel light but the check engine lights then goes off. When off the car won"t start. Occationally the check engine stays on and the car starts and runs for about 5min before stalling. What could be the cause? I can"t check ECM for trouble codes because the light won"t stay on long enough. I might of inadvertantly jumpered the ALDL after I turned the key to on position. I hope I did"t kill my ECM. What should I do to get my car running again? Help?