2001 Ford Taurus Cranks but won't start.

Engine Performance problem
2001 Ford Taurus 6 cyl Front Wheel Drive Automatic

The battery was low from sitting, after trying to start the vehicle I drained the battery completely.
I replaced the battery and could not get the engine to start (cranks though). I replaced the spark plugs and air intake gaskets, added high grade fuel and checked the anti-theft settings and all accessible fuses-all good. It only cranks but won't start. I hooked up an OBD2 reader and no codes, just icons flashing stating that most of the emissions have not finished their diagnostic runs, probably from not starting. The car was running a little rough before I parked it but it ran. Some one in another forum suggested the alternator or cam sensor.

Any help would be appreciated.

JB