Olds Alero crank no start

I have a 2000 alero and all of a sudden one day the car would crank but not start, I noticed the security light would stay on for a very long time before it went out, not flashing, so I decided to try the spare keys, I got to the 3rd key and it did not work and then I turned it upside down and the car started, so I am thinking the tumbler and ignition switch. The car was fine for a couple of weeks, but I thought I should change them before it does it again, so I started with the switch, I Changed the switch, tried starting, and the car was starting fine put it back together came out in the morning and when I open the door it was beeping like the key was in the ignition and again no start, so I go to advanced get a new tumbler with key did the relearning process after 10 minutes the security light goes out turn the key off, and still no start. I checked all the fuses removed the battery cable to reset the computer I can hear the fuel pump running, tried some ether and the car starts on ether and shuts off so it is not getting gas, I just need some ideas on where to go next, no trouble codes no security light and no start