bad fuel econ! please help!

I have a 1993 Civic D15B7. My gas mileage stock for some reason was not good at all. One time i got 231 miles and the most i got on was 361. It's an 11.9 gallon tank and the stats say 29/36 with 1.5liter a/t. calculated it is 345 miles in the city and 432 on the highway. Granted the 231 was in a cold winter with stop and go. The gas gauge jumps around a lot too.. by the time i have 100 miles the needle has already moved past the F. whenever i make a left the gauge swings up, but whenever i make a right, it swings downward!

A few weeks ago I got a K/N air filter. my mechanic put in some Lucas Oil engine cleaner. I then got 292 on the tank cos he told me to fill the tank fully up and the old stuff mixed with the new stuff. the next tank i got 401, then 386.7 with 2.5 gallons left(theoreticaly i should've gotten 500 miles). It's an automatic, so it sucks compared to a stick. Should I think about getting a manual civic next time? I know it's a 93, it has 178,000 miles + on it. Is getting 330 miles on a tank normal? that's the same as a cadillac, and i'm not getting wicked acceleration either! also how much slower does my at slow the car down vs. the mt civic with the same engine? if the mt D15B7 runs 0-60 in 9.4 with a 17 sec. quarter, can the auto run at least under 12 seconds at 19@75? (like my 97 contour) also how much does the k/n add to the car overall? do i go from 102 hp to 105 hp (94 to 99 hp at the wheel)?

thanks
josh echt

also i have temp probs but that's another post.

you're gas gauge jumping is just the gas moving arounding in your tank.

This has been discussed and is the case with most cars, but usually your gas gauge only reads about 10 of those 12 gallons of gas so that you don't completely run out and get stranded somewhere

I don't see how 330 miles on a tank is bad fuel economy. My car is rated at about 25mpg so I should be getting around 300 on a tank, but I usually get between 220-250.

Also, your car is slow, the slowest that Honda made for that generation, you're never going to get wicked acceleration. And the K&N filter will give you maybe 1hp

Also, your car is slow, the slowest that Honda made for that generation, you're never going to get wicked acceleration.

LoL...funny to me

Your lucky, i only get about 300 at the most..never seen above 315.

gas mileage problems are usually solved with basic maintenence. Common bad fuel economy are based these, assuming there are no major modifications to your vehicle:

1. dirty air filter
2. make sure tires are at correct pressure
3. fuel filter
4. bad o2 sensor

im getting 250 miles per tank and thats driving slow. driving WOT sometimes get me down in the 200. but my car is running rich so i have to do a tune up. ive also got 17s(never buy 17s) which was a bad choice of me to do
btw d15b7 does 0-60 in about 10 sec at the most. slow