2004 Hyundai tiburon won't start!! Plz help

This all started when my wife was driving to
my work and said that the car died right
before she was going to turn into the parking
lot I try turning on the car and got nothing
like if it wasn't picking up gas or no spark I
waited till after work and I tried it again but
stillit wouldn't turn on after a while I could
only hear the starter spinning after that I took
off the starter did a bench test it works took
it to O'Reillys it past three times so I went
back and put it on but still got nothing today
I tried it again and this time the start it was
engaging but it still didn't start so I figured
that it was the crank positioning sensor went
bad another one replaced it but it still
wouldn't start but I did hear a loud backfire it
might be that the car is out of time that or
simply the Ecm/ecu is not working can
anyone help me with this or has anyone
experienced the same situation thank you for
your help. by the way it's a four-cylinder
standard car