My 1991 camaro will not run unless you spray a tiny burst of starting fluid in the throttle body, once started it runs pretty good, check engine on...

 

Rent a fuel pressure gauge and check pressure at the valve under the hood. Im not real familiar with the 3.1s in the 3rd gens, but should be easy to locate the fuel line coming up top. Start with that and post your results back. Have you changed the fuel filter recently? Will it start back up if you shut it off and try to restart it soon after?

Also check the vaccum line at the fuel pressure regulator, make sure its on all the way, and connected at both ends somewhere. Check it for cracks/splits. If you smell gas or see gas in that vaccum line, then the regulator is bad.

 

Scan it for codes, shorting the pins in the ALDL connector to flash the codes on the SES light.

Sounds like the coolant temp sensor may be bad, not telling the ECM the engine is cold, so it can richen the mixture for cold start.