1991 Pontiac Firebird just won, t go

First, is the check engine light on? If so, then that's the place to start. Take your car to AutoZone and have the computer scanned. They'll do this for free.

Next, it's never a good idea to hunt for a problem by replacing parts if you don't know that's the problem. It never works and only costs you money you could've just spent on a mechanic.

Now, when you say "it go dead", do you mean the engine stops or it just doesn't have any power?

I'm assuming you mean it doesn't have any power. This is more than likely an exhaust restriction (converter), or the fuel filter/injectors are clogged.

If you know how to use a pressure gauge, you can check fuel system and exhaust pressure. If you don't, then you'll need to take it to a shop.