OK, so i have a 1989 Camaro RS 305 TBI.
im pretty sure its 165 maybe 265k miles actual mileage unknown due to missing number spce. anyways.
we just spent $550 getting the fuel pump replace and in the process the shop that did it hacked my exaust beyond belief and still didnt fix the problem..
we replaced so far the fuel pump, fuel Filter, fuel pressure regulator, fuel pump relay, ECM, and throttle position sensor.
the car will run but will not idle, let me clarify this, it will stay running if i float the gas but if i let off or hold it steady it dies, we tested it with a fuel pressure guage and it is building pressure then bleeding right back off, is that supposed to happen?
now after we changed the fuel pressure regulator it has began to backfire and shoot flames 2 feet tall out of the throttle body.

What went wrong? I miss my car, can anyone help?

Have you checked the injectors themselves? Have you tested the fuel pressure? If so, what is it? It should read around 20-35psi and it should not bleed right off. Something is leaking. Try unplugging the vacuum line that goes to the fuel pressure regulator and plug off the vacuum source. This will allow the system to run at full pressure. Test the injectors.

yes we checked the pressure it goes up to 10-15 psi where the haynes manual says it should be but it bleeds right off,
we know the injectors work because when i feather the throttle i had the air cleaner off and you could clearly see the injectors spraying and they were spraying pretty strong.
a friend of mine told me ther is a ball valve in the pump that should make it hold the pressure that could be bad but we weren't sure if the system was supposed to hold its pressure or not so if it is it looks like it is going back to the shop b/c they gave me a faulty pump or messed something up in the tank area b/c it doesn't leave puddles...

When you say the injectors spray strong, the fuel that comes out of the injectors is supposed to be misty. The fuel should never drip or come out in balls or condensed amounts. If I am not mistaken, doesn't that engine have the pressure regulator as part of the throttle body assembly. It's not the type that is like a port injected car where it has a round body and a vacuum line and a fuel rail. Doesn't your have a square type rubber regulator inside a housing? It's been a while so I may be off.

yes, it has the rubber diaphram type that is built into the throttle body..

With as many miles as you suggest the car has, the timing chain may have slipped a couple teeth/links. Especially since it does not idle and throws flames in the wrong direction.

Take a compression check, they should be around 120-150 PSI. I'm betting around 80-90 PSI., maybe. Also, vacuum gauge will show a low reading, thus the MAP sensor telling ECM, engine is under load, and teaming with the input, is the TPS because throttle is open to keep running, more fuel is being dispensed.