02 Blazer died on freeway will not start sounds rough when trying to turn over to start

I have an 02 Chevy Blazer with a 4.3 L
Vortec engine it died one day while driving
on the freeway and I can't get it started
anymore it's rough when trying to turn over
but will not start it sputters and backfires a
little bit and that's about it I replaced the fuel
pump with an AC Delco fuel pump I have
replaced the caps and rotor spark plugs and
I checked to make sure I got spark and fuel
going to the rail at least I'm racking my brain
over there so I can't figure it out and I'm
pretty Savvy when it comes to working on
cars if there's anything anybody can do for
me or point me in the right direction at least
tell me what I'm not doing I would be much
appreciated thanks.