How do you change an EGR valve on a 1996 Cadillac STS?

To change the EGR valve on a 1996 Cadillac STS, first ensure the engine is cool and disconnect the negative battery terminal. Remove the EGR valve by unscrewing the mounting bolts and disconnecting the vacuum lines and electrical connector. Install the new EGR valve by reversing the removal steps, ensuring all connections are secure. Finally, reconnect the battery terminal and check for any leaks or error codes while running the engine.