1996 Mazda 626 Will not start

I was driving my 1996 mazda 626 down the highway and it bogged down and died. Now it will not start. I have replaced the plugs, plug wires, distributer cap, rotor, and fuel filter. When I try to start the motor it seems to be getting spark and fuel, but it does not act like it wants to start, it just basically turns over. I can here my fuel pump come on. It was having idling problems before it stopped running, sometimes it would die when idling. Im not a mechanic but I just basically need to know some things to check. I have been told the catalytic converter could be possibly stopped up but im not sure if that is the problem. I would appeciate any help.