o2 data help please!

I have a 1990 Tsi AWD and I'm not getting good gas mileage, I think. I only got 250 miles to a full tank. I'm thinking this is a result of my o2 sensor but I wanted to get some advice before I buy a new one. I have a data logger and it seems to reading normal when cruising, jumping around everywhere. But when at WOT it goes to .00v or .02v and freezes there til I let off. I have been told that the reading should be at .75v or higher at WOT. Are there any things that i should check before I buy a new sensor? Or is my sensor just not working? Thanks.

At WOT you should be more around .9-1 volt. Change that o2 sensor.

I get about 250 miles to a tank on the gsx, but thats with me running real rich. If your car is all stock and you dont drive it hard you should get better gas mileage than that.

Yeah my car is stock besides a hacked maf, boost gauge and a data logger. Ok I will just get a new sensor, just making sure that there wasn't anything else I should check out before I spent $70 on a new sensor. Thanks