1991 camaro wont start?

i have a 1991 camaro 305 tbi automatic and RS. I try to start it the radio comes on lights on dash light up needles move but when i turn the key forward it dose nothing no crank. I don't hear the fuel pump in the back but i never noticed it before real loud any way. The service engine soon light comes on and stays on. The INFL REST light lights up blinks for a few times then stays on. i have replaced the steering when with a aftermarket one. I thought it could be my key or tumblers so i replaced them it has been intermediate the how time but after i changed the key and tumblers it stoped doing it for awhile and i dint have no problems then i just started again seems like if i wait for like ten Min's it will start but not always any help would be appreciated.