Ok so after having Mercedes Benz look at my car for low power problems and rough idle on startup, they told me to change the oil before they will go any further.
Apparently at 4500 miles (supposedly the car says to change oil every 10 k but I don’t like that) my oil is “really dirty” as told to me by the service advisor. So dirty that the code fault they found could be caused by a sensor be covered in sludge and debris. After I refused to pay them $175 for an oil change, he told me that when the tech went to check the dipstick, he found rust on it. He cleaned it off and replaced it and checked again with the same result...more rust. Not good.
At this point I’m beginning to think coolant is getting in the oil or similar which was compounded by one new realization this evening. As I was pulling a freshly filled gas can out of the trunk (while the car was still running) I heard a little rattle. It sounded like debris is rolling around near the muffler. And at this point it’s making more and more sense that my catalytic converter may be clogged and reducing exhaust flow and cutting my engine power.
This is the most reasonable explanation I’ve come up with and I’m not excited. At least I’ve got the factory warranty still rolling right now!