I'm not familiar with the TBI setup, but, looking at the wiring diagram in Haynes, the injectors are ground side switched. This means that the injectors have a constant power supply (12V I believe), and the computer acts as a switch on the ground side of the circuit. I could be wrong, but this
there is no power getting to the injectors unless u ground the injector curcuit.
sounds sort of normal. If the injectors are functioning correctly, they won't fire unless the circuit is completed on the ground side.
That said, basically, what sounds like is happening is that the computer is not completing the circuit, and the injectors are not firing, which means the engine won't start or stalls.
A lot has been replaced, some of which doen't seem to apply to the specifics of the problem here. While replacing all of those sensors, has anyone asked the computer if it can see a problem (ie has anyone pulled codes)? As I said, I'm not familiar with the TBI system, but other computer controlled systems will store DTC's that may lead you to know where the problem lies.
Other systems (I would assumes the TBI system does as well) have "failsafes" in the programming that prevent the computer from opening the injectors if certain signals aren't present. For example, if the computer isn't gettinga crankshaft position sensor or camshaft position sensor (not sure which your engine uses) signal, the computer thinks the engine isn't rotating, and doesn't fire the injectors (after all, it would be silly to dump fuel into the engine if it isn't turning over). Sometimes this signal goes straight to the PCM, other times it goes through the ICM. Have you had the ICM tested? Are there any DTC's related to the ignition system or the CKP/CMP?
If nobody here can post the necessary information, the first thing I would do tomorrow would be to go to the library and see if they have a good manual that you can refer to to figure out exactly how the system works, and maybe even get a step by step diagnostic tree for this kind of problem. I looked up Howell, MI's public library, which claims to have a reasonable collection by
Motor which, if they have the light truck volume for your year, should have all kinds of information.