1998 silverado start and die

[CL-1969c10]

Hello, I have never posted on this site before, so forgive me if I am in the wrong section here. I recently picked up a 1998 extended cab chevy with a 305 and spider injection. Previous owner said that it is on a 95 4wd chassis, and has a 305 with spider injection out of another truck. He claimed that the original engine to this cab/electrical system was also a 305 with spider injection. when I attempted to start it it would fire for a second or 2 and immediately die. it had a security light that would come on for a second or 2 and turn off. I stated by inspecting the Passlock module under the radio, and there were no burnt circuits. from there I tried to bypass it with a resister between the yellow wire and the orange/black wire in the ignition cylinder. that did nothing, so I soldered the wires back up and tried a different way. Another video showed to strip the purple wire going into the passlock module and use a jumper wire from it to a ground and release it when the engine was running. that didn't work either. So I went and picked up another passlock module from a junkyard and put it in as another video had instructed. After that I noticed that the security light had disappeared, but still no change in stating. I have since checked fuel pressure at the rail and have 60. I figured since I couldn't see if it would maintain pressure while running I would replace the fuel pump and filter and figures, that didn't help either. I checked a different thread that said I could check the voltage at the ignition cylinder. It said I needed 12 volt at the white wire, and with the wires un plugged it should have 5 volts at the yellow wire, and the voltage on it should drop while cranking. It had around 2.5 volts to the red/white wire, and the correct 5 volts at the yellow; however the voltage wouldn't drop when cranking. The truck runs fantastic if I pour fuel down the throttle body. And for some reason when I plug a diagnostic reader into the OBD 2 port it doesn't recognize the truck.
This is WAY more complicated then my C10... I don't know where to begin Haha.
Any help appreciated, Thank you.