Chevrolet Repair: Intermittent Fuel delivery problem, throttle position sensor, crankshaft position sensor

Question
Ive been having quite a bit of trouble with my 1993 Chevy silverado. all started last week with an ignition switch going out, that has since been replaced, along with the ignition coil, distributor, fuel pump, etc... now the final problem remains that the injectors will not fire. we have figured a way around it to get the truck to run for a min. what we have done in order to get the truck to fire is unplug the leed from the igniton coil, and then turn the truck over and watch it arc, while we do this you can clearly see the injectors firing, we then re attach the leed to the coil from the distributor, the truck will fire, and depending on how much fuel was let in, it will run, but typically not for long. there is good fuel pressure, but it is as if the computer perhaps just tells the truck to quit working. your thoughts? all of the other stats reguarding the engine are as fallows.
5.7L v8
119 thousand original miles
Ca Emisions controls.
Automatic
is there is any other information you need let me know, and thak you for your time.

Answer
Hi Ben,
Two things come to mind.
First, there is a throttle position sensor, that if it shows wide open, the ECM may think it is a clear flood condition, and not fire them.
I believe you have a crankshaft position sensor, that gives a signal to the ECM for when to fire them. But it also tells the spark when to fire, so I doubt that is the problem, since it fires properly.
Of course, there is the ECM itself, but I have NEVER needed to replace one for that, and it is firing the plugs.
Make sure there is a good ground wire connection from the right side head, or intake manifold, to the firewall.

Van