Engine will not start

The 7.5L engine in my F250, with dual tanks, will not start. I have been troubleshooting it now for a couple of weeks and just can't seem to find anything wrong, and have now run out of ideas. I will provide a list of everything that have tried and the results.

- The engine cranks over nice and hard, so I know the battery and starter are good.
- Both fuel pumps are working, as you can hear them come on when the key is turned on.
- Verified that the fuel pressure is 40 psi at the schrader valve on the fuel rail for both pumps.
- Replaced the fuel pressure regulator, and verified fuel is flowing from the hole when it was off.
- Ignition module tested good at Auto Zone.
- Verified injector solenoid winding resistance on all injectors, they read between 14.9-15.3 ohms, this is cold. Can not test hot as the engine will not start.
- Pulled the connector from all injectors and verified 12 vdc present on the positive wire of each with the key on.
- Verified firing pulses as each injector was plugged in one at a time. No injector caused the pulses to stop. I used your "how to test an injector" article.
- Verified spark at the end of each plug wire.
- Verified that the inertia switch is not tripped.

Spark plugs, wires, rotor, distributor cap, fuel filter, air filter & O2 sensor were all replaced about 6 months ago, and have less then 5000 miles on them.

Thanks for any help you can provide.