My '96 Lumina is idling as if it has a vacuum leak. I have checked the vac lines and no dice. The “security” light is on in the dash, and I wonder if this is connected. I do not see a “service engine soon” light showing.
Clean out the throttle body with an approved cleaner. If I remember correctly, any vacuum leak would turn on the Check Engine.
The security light is something else and is not related to the high idle.