Unfortunately without testing all we can do is guess...How old is the fuel filter? Can you feel both pumps running? If both pumps are running and the car hasn't sat for a long time the fuel pumps are unlikely the problem source, if the car has been sitting for loooooong extended periods then they are prone to gumming/seizing. Is there a reasonable chance the fuel is bad, can you sample the fuel?

Has the boot been replaced under the fuel distributor or the large IAC hose(s) been replaced? I'm thinking toward a large vacuum leak brewing.

Good luck!!!

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