1998 Chevy Blazer wont run

1998 Chevy Blazer 6 cyl Two Wheel Drive Automatic 130k miles

i have a 98 blazer 4.3l 2wd auto, it sputtered and now wont start, I replaced the fuel filter and regulator, the fuel pump is 2y/o and I can hear it buzzing when the ignition is turned on, the truck has spark and cranks strong, but only starts and runs while I spray gumout in the engine, I am racking my brain as to what the problem is, please help me.