1. Vacuum Leaks: Check for vacuum leaks in the intake system. A leak can cause rough idling and lack of power. Inspect all vacuum hoses and connections, and replace any cracked or loose hoses.
2. Fuel System: Ensure the fuel system is clean and functioning correctly. A clogged fuel filter or a faulty fuel injector can cause irregularities in fuel delivery, resulting in rough idling. Check the condition of the fuel filter and replace if needed.
3. Spark Plugs and Wires: Worn-out spark plugs or damaged spark plug wires can cause misfires and rough idling. Check the condition of the spark plugs and wires and replace if necessary.
4. Throttle Body: Clean the throttle body, which can become dirty over time and cause idling issues. Use throttle body cleaner spray and follow the instructions for cleaning.
5. Idle Air Control Valve (IACV): The IACV regulates the airflow at idle. If it's faulty or dirty, it can cause rough idling. Try cleaning the IACV with throttle body cleaner. If that doesn't help, you may need to replace it.
6. Coolant Temperature Sensor (CTS): A faulty CTS can provide incorrect readings to the engine's computer, affecting fuel mixture and ignition timing. Check the condition of the CTS and replace if needed.
If you've recently had work done on the head gasket and the car was running fine afterward, it's possible that one or more of these additional components may be causing the issues you're experiencing now. It's best to have a mechanic diagnose the exact cause and make the necessary repairs.
