Over the last 10,000 miles my cars mileage has gone from 55 mpg (its a CVT) down to 41 mpg and has gradualy lost power and is using assist more. My '94 Metro is blowing it away on mpg!! This is an everything perfectly by the book or better maintaned car, everything means everything. Always OEM fluids and filters. Please dont make me repeat this. Cats and o2 sensors are original. IMA pack died suddenly and was replaced 30,000 miles ago and nothing changed after. Tires OEM at 40PSI ALWAYS. This is a commuter car that is driven the same route 82 miles per day 5 days a week at the exact same speeds with the exact same acceleration and braking habits. Mileage always stayed at 55 mpg. Same fuel from same place always. Tried a different place for fuel for 2 tanks to verify fuel was not the issue. Previously the seasonal fluctuation was about 4 mpg. Clogged cat(s)? Worn o2 sensor(s)? Bad injector(s)? Valve lash? Its not noisy. Does idle kind of rough (3 cylinder...) but not any different than before. I can not afford to just start throwing expensive parts at it. I would like to know test procedures or where to get them for any uncertain suggestions. Car has 91,000 miles and is a 2003 with CVT. Please help me.