Thanks for taking the time to write the detailed description, however I still can't find anything like what you describe in the area you describe. The only thing that comes close is a sensor below the exhaust manifold on the left side of the motor. It sits just above parallel with the spark plugs and sticks straight in. It has a black and yellow wire going to it (pic
Here are some other pics of the area you are referring.
pretty sure this isn't it, but what is it????