why im at a half tank and im at 131 mile on this tank this past few weeks my gas mpg has gone to crap. i replaced the plugs and wires and airfilter and still getting bad mpg all i drive is 2 miles to work and 30 min to school twice a week. whats going on the car feels and drives perfect.

Ho old is your O2 sensor? How old is the catalytic converter? Any codes stored?

O2 was replaced begining of winter and cat has been gutted for a long while even during best gas mileage of 200 at half tank. and codes stored? none have flashed or anything.

Sounds like the car isnt getting warmed up. 2 miles is not a lot of time and the computer is probably commanding high fuel to get the engine up to heat range. You may check your air filter or also trying running some top clean through the engine. Low driving time could build up a bunch of carbon in the cylinders.

but wouldnt the 30 min freeway drive burn it off? i do that twice a week.

oh and what top clean?

Not necessarily, high rpm driving would help prevent buildup but may not burn it off. Here is the link to the top clean post....

http://www.bonnevilleclub.com/forum/...ic.php?t=17556

We have some cars at school that we pull in and out of the shop everyday, and thats the extent of there moving... They have alot of carbon build up on them... They all run like crap... We even run them for a couple hours at a time and this doesn't help... I suggest you get some sea foam or a similar product and clean out the top side of the engine.