Yes it sounds like it would be the ignition switch itself. Now I did work on a '97 Malibu (same system as yours) that was previously bypassed using resistors. Ended up tracing it down to a short inside the instrument cluster. On these sytems, they use a "bulb check" system through resistance that's also tied into the PK2 system. Swapped out the cluster and it's been fine now for over a year.