Anti-theft Controller problems of the 1998 Chevrolet C1500

1998 chevorlet silverado C1500 pickup failed to start intermittently. Problem is related to the gm pass lock ii system. Problem started 1. 5 years ago and has become more frequent. I talked with the local gm repair facility , and they said it would cost between $200 - $6oo to troubleshoot. Replacement parts would be an additional cost. Also, they stated that gm was aware of an occasional malfunction with the pass lock ii system, but gm didn't think there was a widespread problem. This problem has left me stranded on several occasions. This malfunction happened without notice, and sometimes it took anywhere from a few minutes to several hours for the malfunction to correct itself to the point where I could start the truck. I have replaced several parts related to the pass lock ii system, but the problem still persisted. Gm offered no help.