The car is fixed and I thought I would share the result with the forum.
After taking the intake off for the 2nd time and:
1. Replacing with another new injector
2. Checking the wiring
3. Did a mini-tune up by replacing all spark plugs with iridum plugs (may as well, had the intake off anyway)
The car still had an open. I suspected the ECM module, so I took it to my Cadillac dealer.
It was a good move, as it was the ECM Module and the ECM was covered under the warranty if the car has under 88k miles.
The fixed it under warranty and it is running great.