[94talonawd]

The 02 sensor isnt going to affect gas mileage much. My 02 went out for a while, and I didnt even notice any change in Gas mileage. Check for any vacuum leaks and boost leaks. And the other thing you should do is get a pocket logger and see if your car is running ok. There could be many factors involving poor gas mileage. Check your base ignition timing. Also check to see if timing gears are aligned correctly. I would also check your manifold, it might be cracked. Also check your turbo, it might have gotten fucked up on you. Check the wastegate on the turbo to see if it isnt stuck since you arent reading any boost. I would also check the emmission lines for vacuum leaks.

Again, I am not too sure if the ones stated above would solve your problem. But atleast, this is what I would do to check.

I hope this gives you somewhere to start, and good luck.