Code P030, ISC Rpm Out Of Range: Notes
WARNING: This page is about a different car, the 1995 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
PCM controls engine idle RPM by increasing or decreasing throttle opening using Idle Speed Control (ISC) motor. ISC controls idle speed any time throttle switch is closed. Code P030 detects engine RPM out of limits.