91 firebird starting?running prob..help

[qixstix]

I was driving my 91 Firebird down the hiway and it shut off..it has electrical power...I tried to start it and it idles super rough and shuts off..when tested it had 30% pressure..I replaced the fuel pump which made it go up to 45%..still runs really rough..and dies..any ideas ? i mean..it was running like new...shut off, now running like crap..no noises occured before it shut off...

 

[melsg5]

I assume you mean psi not %? Did they check for any computer codes? Did they replace the fuel filter? which engine?