bad mileage. Oxygen sensor?

[84LX89GT]

First off i'd like to say it's funny seeing someone using 84stangLX because that used to be my username when i only had my LX and not my GT......anyways, now to the point.

I had a '91 LX 2.3L 5 speed and it would AVERAGE 21 miles per gallon, i kept track meticulously.

My '84 5.0L LX would get 16-18 miles per gallon with a 5 speed and holley non-emission 4 barrel.

My '89 GT now currently AVERAGES 19 miles per gallon.

I think the 2 mpg difference it not worth the 110 horsepower 165 ft/lb torque difference and increased handling/braking of the 5.0 package (well, increased braking in the '85+ models i believe). Welcome to the slow world of the 2.3L mustang. I believe that the 2.3L was mostly meant to lower the emissions for the mustang model line and also to attract a lower budget buyer. I was also surprised by how crappy the mileage was. Another thing that sucks is that they're gutless and the "power" if you can even call it that runs out EASILY by 4000 rpm.