Code P030, ISC Rpm Out Of Range: Notes
WARNING: This page is about a different car, the 1995 Cadillac DeVille. 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 motor controls engine RPM any time throttle position switch is closed. Code P030 sets when actual RPM never reaches desired RPM signifying a slow or failed ISC motor.