When the powertrain control module (PCM) or the battery are disconnected, the PCM loses power, or the PCM is reprogrammed, and the PCM's learned idle position is lost. When the learned idle position is lost, the engine idle is unstable

Perform the following procedure in order to return the learned idle to the correct position:

Automatic Transmission

1. Turn OFF the ignition.
2. Restore the PCM battery feed.
3. Turn OFF the A/C controls.
4. Set the parking brake and block the drive wheels.
5. Start the engine.
6. Ensure that the engine coolant temperature is more than 80°C (176°F).
7. Shift the transmission into Drive.
8. Allow the engine to idle for 5 minutes.
9. Shift the transmission into Park.
10. Allow the engine to idle for 5 minutes.
11. Turn OFF the engine for 30 seconds.

Manual Transmission

1. Turn OFF the ignition.
2. Restore the PCM battery feed.
3. Turn OFF the A/C controls.
4. Set the parking brake and block the drive wheels.
5. Place the transmission in Neutral.
6. Start the engine.
7. Ensure that the engine coolant temperature is more than 80°C (176°F).
8. Allow the engine to idle for 5 minutes.
9. Turn OFF the engine for 30 seconds.