How do you tune up 2005 Cadillac CTS?

To tune up a 2005 Cadillac CTS, start by replacing the spark plugs and ignition coils for optimal engine performance. Check and replace the air filter and fuel filter as needed to ensure proper airflow and fuel delivery. Additionally, inspect and top off all fluids, including oil, coolant, and Transmission Fluid, and consider running a fuel system cleaner to remove any deposits. Finally, perform a diagnostic check to identify any error codes and address any potential issues.