Firebird wont idle well, or dies like the fuel is being cut off.

Good times are over, today I lost power coming home, the car will Idle fine but sounds like its missing out and there's no throttle response except to die. But,, there are times it will start and run absolutely perfect and smooth but with a lot of backfire, but not for too long. it loses power again and I seem to smell a lot of gas. I seem to be having a key or ignition cylinder short too. It has been replaced before. Also I had just put stop oil leak in as I have a small leak on the back of the motor on the passenger side right before this started. Any Ideas? It starts every time, and runs perfect or only Idles with no power. no power 80% of the time. so frustrating

no I haven't checked the fuel pressure, something seems to be messing with the fuel pump. maybe tomorrow.

also just getting the code 12. man oh man

Okay hope this narrows it down a bit. Checked fuel pressure, 42psi with key off or in power position. when priming 48psi. When just idling with no power or throttle response (just bogs down) It's at 42psi. After restarting it about 10 times, It fired over and is running great and drivable at around 40 psi. Has full power, But a lot of backfire? It has a new sending unit, new fuel pump relay, new oil sending unit, new distributor and rotor. I think I had the Ignition module checked last year and it was okay. I took apart some kind of round breather connected to the sending unit rail and cleaned it when I installed the unit. Did I tear it up messing up the breathing of the tank?? It ran great for about 2 months, then this. Help!! lol

I also bought a new key and cleaned the ignition cylinder so I hope I can rule out the short on the steering column and the fuel pump.

I hope it is running ok, my mind is spinning after reading everything.

not yet,lol. Just replaced the TPS, no go. I can spray gas into the butterfly and the car runs perfect. I'm showing code 33. I have a feeling I have fuel injectors bad since I have good pressure at the schrader valve. They are 21 years old.The car will just Idle now Unless I spray gas into the plenum. So sick of this, I have $1500 dollars worth of new parts on it when this happened. Sick in KY,,,,

Code 33 is for the map sensor. Check vacuum and circuits at the map sensor connector.