I've pretty much determined that some part of the ignition lock cylinder is not reading the pellet properly and that is what is creating the intermittent no-start problems. The local GM dealer says they want around $500 to repair. I had a new key made to no avail.

Does anyone have any info or pictures on replacing the lock cyl part that reads the pellet? From what I've found from google searches, it appears that the part that reads the pellet is what needs replaced.