How are you doing the cranking tests? I am wondering if there is an issue with the ignition switch itself. When the key is in the "RUN" position you have all three, air, fuel, spark, but in the "Start" position fuel or spark is not happening. I know you are saying you have spark, but is when someone else is turning the key and you are watching? Or when you bump the engine over from the engine bay with the key in the "RUN" position?