I would check fuel pressure, you need 35 psi at idle, blipping throtle should give you an increase in fuel pressure, 45 psi max. Disconnecting fuel pressure regulator vac line, should show 45 psi. If not, fuel pump is suspect. I would also check the condition of the crank position sensor if the 91 has it, replace if it looks suspect or is like 10 yrs old (they are cheap). Also, check, just to be sure that your main fuel relay (behind ashtray) is good. Remove it, pop cover off and look for cracked solder joints, resolder or replace.