98 chevy cavalier cranks but wont start changed fuel pump,computer,crank shaft position sensor and the theft system light is staying on

Turning the key without starting it untill you hear the fuel pump stop (it will make a humming noize this is the fuel pump pressurizing the lines) then immeadiatly after it goes off turn your key to the off position repeat this 3 times then your car should start

Try to start the car, than the anti theift would shut the car off. you wait ten min with the key on, until you see the anti theift flash or disapear. than turn key to off position and try to start it. this will reprogram the computer.. Good luck.

you can also try disconnecting the battery for 30 minutes