I have a 1992 LS400

Ok, heres the situation, the other day I got a Check engine light and it was code 71 (EGR). The car was hesitating throughout the RPM range, and idled rough (as if 1 of the cylinders wasnt firing.)

Cleaned out the EGR and cleared the code from the ECU. Car still ran rough, and the check engine light came back on about 10 miles later.

I checked the codes and I dont have the code 71 anymore, but now I have a code 25 and 26 (didnt have it before when i had the code 71). Which I read up on and usually that means replacing the o2 sensors.

Now, Would the code 25 and 26 have any corrolation with the code 71? I just want to know for sure before I spend the money on 4 new o2 sensors.

Is it possible for all 4 o2 sensors to start to go out all at once, hence giving me a code 25 and 26?

Also, would replacing the o2 sensors fix the code 25 and 26, or could they be related to something else?

Any help is appreciated, thankyou!

By the way, the codes are :
25 - Air-fuel ratio lean malfunction
26 - Air-fuel ratio rich malfunction