Terrible gas mileage

I dont know if this is the right thread but whatever, so I've been getting terrible gas mileage lately, i fill up my car to half way, drive across town to a friends house and back (mostly back roads not many stops) and by the time i get home, swing by the gfs (who lives pretty close) and back im almost on empty. It's ridiculous, for the most part i baby my car unlike some people who like to pass cars in one lane roads on hillside curves *ahem* COROLLAGT *ahem* (bastard almost got us killed) I'm wondering if you guys can list some stuff i can check aside from the obvious.

guess im gonna check the spark plugs, air filter, and check for any leaks.

What's the mileage of the car?
Any recent repair work or new parts installed?
Any new additives you were trying out?
What sort of mileage decrease are we talking about - 10% sort of drop, like going from 33MPG to 30MPG or we talking 50% or more?

Mileage fluctuations of 5-10% are more or less in the noise, 10-15% or more is common with winter blended gasoline (summer blends are being reintroduced to stations starting in March). But if you see a consistent 20-25% or more decrease, likely be something mechanical and/or electrical.

If it started suddenly and nothing else was changed on the car, could be a case of a lazy or dying O2 sensor. O2 sensor can degrade enough to not work correctly, but not completely fail, as to set a CEL.

I was getting like <20mpg but then I cleaned my air filter and mpg improved dramatically.

I really do need to check the tire pressure, good idea. The car has 123XXX miles on it, other than changing the transmission oil and differential oil no other maintenance was done except tie rods being replaced but I dont think that should affect gas mileage. About 15% seems right, and the car has no MAF sensor, dont let the front end fool you, its a 99.
Added: Apr 11, 2011 6:49 PM
Thought sometimes when I accelerate I can smell either gas or oil from the hood, I dont know if im smelling things or its from another car or what.

might have been mentioned, but have you done a major tune up?

Nope, but I need to hopefully this weekend. Gonna clean the air filter today its just a pain in the ass to get to.

at 123k miles i would definitely check everything from the throttle cable to the exit of the exhaust. make sure you're not smoking out the exhaust which could be a sign of other problems.

You mentioned you did tie rod ends recently? You did get an alignment right?? If not you're toe might be out of adjustment and not only will it eat the tires.. but it will kill your fuel mileage also.

Yeah, of course i got a 4 wheel alignment.

Try running with your feet pigeon toed next time, thats how.

Also today while inspecting the engine bay I discovered my CAI piping had come undone at the throttle end because the battery was pushing up against it. So I re-arranged my battery and secured it better so it wouldnet wobble into it and push the intake end piping off. All of the clamps I had were too small to fit around so I'll have to purchase one to make sure it never comes loose again. Doubt thats the reason for my mileage but I also filled up my tires today and my gas tank, will see how things go in the coming days.

Im pretty sure it does have a MAF...... ? Should be hooked up to your intake...

huhh, interesting. where is the map sensor located? and would the maf be where the map used to be?

Oh, I made a hole in my intake for that sensor. I figured it probly needed it for the proper fuel mix. that might be why you have crappy gas mileage.

But dont forget to take lots of pics from them drop.lol AND POST THEM ALREADY!!!!!!