for a few months now my car has taken a long time to start(3-7 seconds)
I replaced the oxygen sensor and Ive cleaned the throttle body.

Also somtimes the security like will stay on but it never fails to start just takes as long as normal somtimes.

Have you checked your fuel pressures? Put a guage on it and see what kind of pressure you're getting with the key on (not running). It should be between 42-48 lbs.

sounds like the beginnings of a potential Vats issue, since the Security light is popping on...

clean the Key, use a spare if you have one, and also clean the ign cylinder

yea I am going to check the fuel pressure.
How do you check to see if the FPR is bad?

Pull the vacuum line off. If you have fuel come out of the vacuum side, it'* definitely bad.

With mine, I figured out it was bad when I would let the car sit overnight, and use the schrader vale/test port to see if there was any pressure left after it sat. No pressure in the morning = bad FPR

Just an alternate method....

<Important Edit!!> With either method, have some rags in your hand to catch any fuel that may potentially spill! I've heard rumours that gas can be fairly flamable....

With this in mind..the FSM mentions that the pump can also cause pressure to bleed down. One of the seals...

your car is really hard to start. have you tried turning the key to on, letting the pump energize, then starting it?

we can check fuel pressure on tues along with the other chores we have to do.

can you rent a fuel pressure gauge from advance or auto zone?

Try turning the key on for a few seconds, then off and repeat a couple of times to let the pump bring the system back up to full pressure. See if that guarantees a quick start.

A lot of the time, an extended crank condition can be narrowed down to one of the following:

1 - Fuel Pressure Regulator. Pull the vacuum line off of it. If it smells like gas or fuel dribbles out of the regulator OR the vacuum line, the FPR is bad.
2 - Fuel Injector. If a fuel injector is stuck open, it will leak down all the pressure into the cylinder. A massive backfire can occur if this is the case.
3 - Fuel Pump. There'* a check valve in the fuel pump to prevent fuel from leaking back into the tank. If the check valve sticks open, the fuel pressure will leak back into the tank.

Your best bet to narrow down the cause is to get a fuel pressure tester. Put it on the scraeder valve, start the car, shut it off and watch the needle. If it doesn't fall, it'* not a fuel delivery issue and more likely a VATS problem. If it does leak down, check the FPR. If that isn't leaking, pull the injectors and the rail (in one assembly -- don't seperate it! you don't need to, and it makes reassembly more difficult). Turn the key on to build fuel pressure and see if the injectors leak gas. If one of them does, you can either replace it or find a shop that offers a BG Fuel Injector Cleaning. Great product, I've used it at my shop for years. Takes care of the typical fuel injector problems found in GMs. If none of the injectors leak, you're looking at a fuel pump.

Any questions, lemme know. Good luck.

EDIT: Another way to determine if it'* a fuel injector leaking is if you have a misfire. The misfire is being caused by the excessive fuel leaking into the cylinder and fouling out the plug(*).