Cranks will not start

My car was hard starting and even backfired but started up and ran good once it warmed up now I cannot get it started. It wants to start but backfires and sputters a little. I had the timing belt replaced seven months ago and I am not sure if it is the timing or bad wires? Or plugs or maybe even a distributor problem. What do you think might be the problem? I did recently overheat the car as my radiator went but once I replaced it it was running fine. It seems to be getting fuel as I can smell it when I hold my throttle to the floor. So it is cranking and want to kick in but spits then back fires. Please advise