2010 Forester. 185k miles.
I had the P2097 code and another one that said too rich instead of too lean. Bad gas mileage, CEL, flashing cruise. I replaced the MAF and rear O2 sensor with no affect. Just replaced the front O2 sensor and it's been running great for a week or so!
Just buy whatever hitch and cut/weld in the receiver tubing size you need for the carrier.
You might need heavier rear springs if you also have any gear but KING springs makes some.
GD