94 F150, 4.L 6cyl, 4x4,

My name is Mark, I'm new here, this is my first day. Thank you for allowing me in. I'm a lifetime mechanic, automotive as well as diesel and heavy equipment, retired. And this Ford is really got me stumped. I need your help. 
It's a 1994 F150 with the 4.9L straight six, its 4 wheel drive, gas motor.It will crank like crazy but it just won't start. I have replaced the ignition control module, the distributor and cap, the wires and plugs, the coil, now the ECM/PCM. Still won't start. What am I missing/
Please help if you are able. Thank you.

Hey Mark! Welcome to the forums. I moved your thread to the Repair section for more traffic.

I'd say it's time to go back to square one. What are you missing? Spark, injection pulse, fuel pressure

Does the MIL turn on?

If you have a scan tool, can you command a KOEO Self Test? What are the results?

That's what i'll do now. Be back to you asap. Thanks