First off, let me apologize if this is already in the archives. I searched a few different combinations of keywords, but couldn't find what I was looking for.

My '94 854T's fuel efficiency has gone down considerably. It used to be around 23.5/27.5 (cty/hwy), but is now averaging about 22.5 for mixed driving that includes both. (For DC-area people, I take I-66 to Fairfax in the mornings from DC, and take HWY 50 back.) It is true that the car has gotten older, obviously: it's currently at about 130k. But I drove the car cross-country from WA State to DC, and averaged about 22.5 according to the trip computer, even though 90+% of the drive was on interstates, with cruise control. I have always used 91+ octane gasoline, with no ethanol. I am not a leadfoot, and use cruise control everyday.

This is one of those cars that has always had the Check Engine light on--to the point where my mechanics have told me to ignore it. Pulling codes usually resulted in something knock-sensor related. I have had the knock sensors and wiring replaced/updated by a dealership. The engine idles smoothly. Acceleration is perhaps a tad below where it's been in years past, but I attribute that to age. I was told recently by a mechanic that he pulled an 'evap' code.

What should I do about this? Is it something as simple as spark plugs? Any advice would be much appreciated.

Mendelssohn
'94 854T ~130k