Where is ignition coil on a 1990 Chevy lumina 3.1?

On a 1990 Chevy Lumina with the 3.1L V6 engine, the ignition coil is typically located on the passenger side of the engine, near the distributor. It's often mounted directly to the distributor or very close to it. Because of its age, some components might have been replaced, so it's best to check visually. Looking at diagrams for your specific year and engine would also be beneficial. You can find such diagrams online through sites specializing in auto repair information (often requiring a paid subscription) or in a repair manual specific to your vehicle.