The problem as I see it is that you’re trying to treat symptoms instead of the cuse(s) of the problem(s). You’re trying to make the light stay off instead of fixing what made it come on in the first place. You either need new catalytic converters or you need to reinstall both oxygen sensors properly, without spark plug defowlers. Then, after you’ve got good cats and good sensors, if you still get a code, you need to diagnose the cause of the code and fix what is wrong.
I know Chilton, Haynes, and the other repair manual publishers have gone downhill, but if you need help identifying components under the hood, that is still one of the few things those books are good for. I tried searching online for engine diagrams for this model, but they don’t seem to include that component. As a last resort, take a picture of it, take the picture to the parts store, and ask the guy behind the counter if he can identify the part.