The check engine light was not working. So, I replace the ecu. It is now working. No codes show. Assuming switching the computer meant I had to up date the key encoding, I contacted a locksmith. He gave me instructions on how to update the key.
Now the car acts like it wants to start. However, it seems to kill the spark and fuel right away. Which could be the CPS. But it checks out okay. So, I'm still searching anything and everything.
What instructions did the locksmith give you to program the key to the car's computer? It was my understanding that on a Catera, you have to go to the dealer to get it properly mated. When you try to start a Catera without the key programmed, it acts just the way you have described.