Unstable Idling: Hunting
- Check spark plug for improper gap or fouling.
- Ensure there are no vacuum leaks into intake system.
- Check EGR Control valve operation.
- Ensure engine has adequate compression.
- Disconnect exhaust gas sensor and monitor change in driveability. If it improves, replace sensor. If not, go to step 6).
- Enter self-diagnostic Mode II and monitor exhaust gas sensor operation.