Pontiac Repair: Help me please my car wont start, pontiac sunfire, car symbol

Question
I have a pontiac sunfire 2001 2.2 l coupe I had gone shopping I was gone for about 20 mins and when I came out I tried to start my vehicale. It would crank fine and every three times i tried to start it it would start for a second then turn off/ I would try to rev the engine and it would let me rev it once then shut off. I put fuel injector cleaner in it and changed the fuel filter neither one worked. The lights that come on that never did before are the service light and a car symbol with a lock they both stay on and dont blink or anything. It has oil and gas and I have no idea what it could be a mechanic who had come to look at it doesnt think its the fuel pump but something electrical maybe with the antitheft system if you have any suggestions please let me know I dont have much money and would like to get it fixed without spending to much thankyou so much.
Lynsey

Answer
Hi Lynsey:
is the security lamp on and or flashing when it dies out? if so just leave the key in the run position for 20 minutes and the lamp should stop flashing and or go out it depends on the year car as to what the lamp does after the lamp goes out or stops flashing turn the key off for 1 minute and then try to restart it it should start and run. I think the issue you have going on here is the factory tehf system is messing up on you. if the cars does start and run then the ignition lock cylinder is usually the culprit the part is not that expensive nor is the labor. good luck :)