i have posted this problem before but i tried everything and still came up with nothing.

1990 firebird v6

i was driving down the street, i hit a slop right turn i let off the gas and midway through the turn i hit the gas again, as i did this my problem started.
it starts fine, idles fine for about 5 or 6 min.
i can even drive it for a certin point but if i punch the gas to fast it will start to die and you'll hear a back fire sound from the engine area (somewhere around the first spark plug).
when driving if you slow down to go over a speedbump for example it seams to run normal for that couple seconds before the speed bump.

i replaced the rotor, cap, spark plugs, wires, and fuel injectors all with new ones.

maybe its my fuel shutoff valve?
i give up...
any ideas?

 

Fuel shutoff valve? Did you add one?

You might want to monitor fuel pressure for variations and pressure.

Have you changed the fuel filter recently?

 

no i didnt add a fuel shut off valve, some guy down the street told me it might be that, i dont know if i have one or not...
oops i forgot to metion my fuel pressure is good, and throttle position sencer is reading fine. no i havent change my fuel filter recently.

 

There is no factory installed fuel shuut off valve on our cars. The ECM will stop pulsing the injectors to kill fuel when necessary.

I understand that the fuel pressure is "good", but exactly what pressure is there under what conditions? It might not be as good as you think.
Since you have a general performance issue, you should verify a good ignition system. I see that you have replaced most of the significant parts, but you should also inspect or test the connections at the distributor and EST module, test the coil, check/set the TPS voltage, clean the throttle body and IAC, inspect/test the pickup coil and reluctor, possibly test the HEI module, the and inspect all the vacuum hoses. If you don't find any problems with those, you can be relatively certain the ignition and control systems are operating. That would make the fuel system the more likely suspect. Again, a clean fuel filter is necessary to maintain adequate pressure and flow, and is part of normal maintenance. If you haven't replaced the filter in the last 25,000 miles, it's due anyway.

 

in case you find this thread in the search i found my problem to be the ignition modual. i replaced it and it ran fine again.
kinda ticked i spend almost $500 on a $28 Dollor (5min.) job...