Just got ls 400 1992 with 162k miles and check engine light came on shows code 25 and TRAC OFF I changed the down stream O2 sensor and nothing change I heard that it could be the MAF SENSOR or The UPstream O2 sensor any suggestions ?

 

http://www.lexls.com/tutorials/intro/codereading.html
25 - Air-fuel ratio lean malfunction

it could be many issues and throwing parts at it is expensive, but i think you're on the right track with the o2 sensors. however the car has 2 downstream sensors, and 2 upstream as well so which one is it?

which one did you replace so far? since you have a new one, swap it to the other side. you cannot use a downstream sensor upstream and vice versa, but you can swap left to right.

 

and forgot to add that when starting the car rpms are around 800 900 and when warming up and rpm goes down, the car wobbles like it is going to stow but then around 400 rpm it becomes stable but time to time it shakes a bit

 

There is a simple test you can do for Code 25 to test your upstream o2 sensors with a multimeter

I posted about this in February
https://www.clublexus.com/forums/ls-...l#post11675188

My car got code 25 a little over a year ago. I found my left bank upstream o2 was lazy after the test