Engine misfires, rough idle, minor hessitation upon acceleration

My '99 Firebird V6 3.8 ran excellent up to about 6 months ago when it started throwing service engine lights for P1441 emmissions code, replacement of the gas cap made the light go off. The code came back, has stumped 3 dealerships and 4 race shop mechanics.
Engine hessitates to start, gas smell intense, black smoke from exhaust at startup, idles intensely rough for 2 seconds, then switches over to a somewhat smoother idle with what appear to be skips or misfires.
Plugs and wires had been replaced, car received complete fuel injector and engine enema. No change. Does not accelerate very smoothly.
Considered a fuel pressure regulator replacement, I believe it may be related to some sensor miscommunicating to the computer. Computer was recently reflashed following Cat replacement. My 2nd '99 Firebird V6 3.8 does not have any such problems after a plug and wire change, new Cat and reflash. Yes, the plugs and wires were stock replacements and "professionally installed by a certified Michigan Mechanic".
All mechanics have been stumped and I'm out $500.00...:brick:


Also how does one replace a multifunction switch that has a ghost short that knocks out the 15amp A/C and Cruise control?
GM does not list a picture of the replacement part, and it is not a stock item. Aside from that the dealership claims after diagnostic there is only an 80% chance replacing the switch will resolve the shorting issue:cuss:

My neighbor had a problem like this on his v6 and it was a coil that was bad. Not saying that this is your problem but it may be something to check into. They are fairly easy to remove and autozone will check them for free.

Emissions codes and running rough? Sounds like my first guess would be an O2 sensor going bad.

Pm experiencing the same problem... where you ever able to resolve this problem?

Matt

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Originally Posted by skintox

My '99 Firebird V6 3.8 ran excellent up to about 6 months ago when it started throwing service engine lights for P1441 emmissions code, replacement of the gas cap made the light go off. The code came back, has stumped 3 dealerships and 4 race shop mechanics.
Engine hessitates to start, gas smell intense, black smoke from exhaust at startup, idles intensely rough for 2 seconds, then switches over to a somewhat smoother idle with what appear to be skips or misfires.
Plugs and wires had been replaced, car received complete fuel injector and engine enema. No change. Does not accelerate very smoothly.
Considered a fuel pressure regulator replacement, I believe it may be related to some sensor miscommunicating to the computer. Computer was recently reflashed following Cat replacement. My 2nd '99 Firebird V6 3.8 does not have any such problems after a plug and wire change, new Cat and reflash. Yes, the plugs and wires were stock replacements and "professionally installed by a certified Michigan Mechanic".
All mechanics have been stumped and I'm out $500.00...:brick:

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