I have a My00 Impreza... with Afc, and gauges. I have the check engine light staring me in the face. I took the AFC off and i still have the CE. I was wondering would i have to take the gauges out also when i take it to the Dealer.

try resetting your ECU first. that might get the check engine light off

Tried that multiple times... I may aslo add.. I am getting terrible gas mileage which isn't too new the for the car but it is running rather Rich

Maybe a busted O2 sensor or wire? Because you would get bad gas mileage when O2 sensor goes dead. S-AFC connects to a O2 sensor wire. Maybe the wires came loose or something.