Sounds like your truck is OBD-II (EEC-V). Not sure if it still uses the IDM signal to tell the PCM The coil is firing. Midway down the page on this link: http://fordfuelinjection.com/?p=6 shows the diagram of the IDM signal. If the PCM does not see the coil firing one would assume it would not fire the injectors? I am no expert on the EEC-V, but I do understand electronics. You might need to invest in Service and EVTM manuals. I am away from mine until this weekend. This may sound like a stupid question, but are there any codes now?