06 3.0 Mazda 6 shut off while driving, will crank but not start
 

Hello all, I have a 06 Mazda 6 that shut off randomly one day while I was driving and will not turn back on. It will crank but not start, I've had the battery tested and alternator and they're both good, replaced crank and cam shaft sensors, tore engine apart, checked for fuel on spark plugs and spark on spark plugs, all are how they should be. I've searched high and low for the cause of the problem. Any suggestions? Thanks in advance