After a lot of messing around with it and all the help I got on here I was able to greatly improve my mileage. After I did a tune up, that didn't seem to help much, so then I got a new O2 sensor and put that in. Then I was still getting a CEL and a 43 code. Finally I messed with the vacuum hoses until I got them right, and everything runs great now. The car now Idles at 700 rpm instead of the 1500-2000 it was doing before. For city driving I am getting about 26-29 mpg, and on the highway I have been getting an amazing 35+ mpg. This last fill up I have gotten the best mileage yet, I swear I think I may get over 40mpg. All in all I am very pleased with the increase, and I won't complain about 25+ in the city for a b18a engine.