DYI steps please - 97 Pathfinder Oxygen Sensor and Throtle Position Sensor

o2 sensor (depending on which one you are replacing) will be right on the exhaust pre and post cat. go to your local auto tool supplier and buy an o2 sensor socket. i changed the 2 rears in my '98 in about 1/2 hour from start to finish. Fronts look a little trickier but still doable. just need a couple extensions. Also to break the one side free on the rear o2's I used a 12" breaker bar on my ratchet. and just gentle steady pressure broke it free.

How do you know your TPS is bad? error code?

seems i suffer from the same problems as you, and many others with the low fuel economy...at least in part mine can be attributed to a heavy foot. I don't believe (or at least can't train myself) to lighten up my foot on acceleration. I have taken most of the same steps. Replaced the plugs and wires, replaced the air filter and fuel filter. Replaced the rear o2 sensors and still have to do the fronts. I want to attempt cleaning the MAF sensor as well but am a little scared of damaging it. Also, I am going to do the distributor cap/rotor, which i have heard is good to do when the plugs/wires are done.

update with whether or not there was an improvement as i still have to do my fronts. I am curious as to whether you would see a significant difference.