Where would you find an O2 sensor on 88 camaro engine 2point8 Multiport V6?

On a 1988 Camaro with the 2.8L Multiport V6 engine, the O2 sensor is typically located in the exhaust manifold before the catalytic converter. There's usually only one on this engine. Look for a threaded sensor, often with a single wire harness leading to it, somewhere along the exhaust manifold's tubing, close to where it exits the engine. You might need a wrench to access it better. Since it's before the cat, it'll be on the exhaust pipe relatively close to the engine block.