1991 Chevy Camaro Cranks but will not start

I am trying to diagnose a cranks but will not start issue with my camaro. I have checked extensive items on the vehicle which include:

TPS
CTS
MAP
MAT
All of the above mentioned items checked out OK. I checked for the reference signal from the ECM and for the ground and the signal back to the ECM from the sensor. I have 40PSI of fuel pressure at the fuel rail. The fuel pressure is steady and does not bleed down.
I have spark from all 8 plugs.
I do not have any trouble codes.
I do have the "check engine" light present when the key is turned on and it does flash code 12.

I used a noid light and checked for injector pulses at each fuel injector. Pulses are present at each injector. The car cranks over fine but does not start, if it does start it will run very rough. If you disconnect any of the 8 fuel injector electrical connectors the car will start immediately but run very rough. As soon as you plug the fuel injector electrical connector back in the car will immediately stall. I tried a new ECM but that did not correct the problem. Any help you can offer is greatly appreciated.

Thank You,
Grant