Free code reading in town?

[Phy]

The background: My Nissan's been acting up recently, where it will suddenly lose all power if you step on the gas, and if you leave it alone, it bounces around 1000 rpm for a minute or two until it resumes normal operation. It's only done this a couple of times, and the rest of the time it runs normally, AFAIK. If the computer's caught something obvious, I'd like to know about it.

The question: Is there anywhere in town (like, auto shops or part stores) that will read ODB codes for free?

[3G]

Auto Value does it, are you throwing check engine lights?

[Phy]

I throw check engine lights all the time because my O2 sensors are shit. (Well, one's shit. The other one isn't even in the cat.)