Why does my car stall so much? on 1996 Buick Century

My car stalls most of the time. One day it'll start and run for 2 or 3 days and other times it will not start at all. I replaced the fuel filter,I had the ignition coil tested it's good,spark plugs are ok I am at my wits end right now. Please someone help me!

Asked by for the 1996 Buick Century