89 firebird 305 tbi will fire over but dies and will not even go to idle

okay i have replaced the fuel pump filter feul presure regator ecm rebuilt the starter and put in a new ingition switch on a 1989 ponatic firebird 305 tbi and now it is firing up but it will just die after wards and if i hit the thottle i can keep the car running

This may sound silly, but have you tried unplugging the battery to reset the ECM?
Im not sure if the tpi 305 has a MAP or MAF sensor or both, but one of these sensors could be the problem...
Did you ever manage to pull any trouble codes?...Often times if one of these sensors go out, it will be a while before a code actually pops up...