Received a bad AIT Sensor and have been looking for this on my 1997 Maxima. Seems I've seen 4 or 5 different places, but this newbie to car repair can't seem to locate it..unless I've circled them in the pics. Everybody says it's easy to fix, but I'd need to take off the top portion of the air filter, MAF, and some move other things around just to get to it. Do I have it correctly located?? Its near the elbow down from the intake and under the MAF. Forgive the general filthiness.

Yes, that is it. Good job on finding it yourself.

You should be able to pull the sensor out along with the grommet that holds it in place. Then just pop it back in.