My car has been sluggish lately and my cel came on about 2 weeks ago for the first time and it was rear heated o2 sensor but my car seemed to run noticeably worse after that cel came on. I have read on other post that the rear heated o2 will have no effect on performance but something isn't right with my car. I am getting the rear heated o2 and knock sensor when doing the cel check but I have read numerous times that the KS probably isn't bad. So I will tell you guys the symptoms and tell me what you think:
(1) When starting my idle will be normal then drop to 500rpm and hold steady, but it feels like it is about to die.

(2) When put in D or R the car normally will go by itself(roll slowly) but I have to give it alot of gas to get it to actually go.

(3) Power has surely gone to, even though the rear o2 isn't supposed to affect performance.

Anyone think my Cat. could be bad? Doesn't that really hurt performance even though there is no code?

Any help would be appreciated. I am tring to get as much info as possible b/c cause I want to fix this myself.
I have recently cleaned the TB. Also tried the cleaning of my rear o2 w/break cleaner.
'95 auto 98K

When was the last time you did a tune-up?
The O2 and knock sensor code put the car in safe mode delaying timing therefore making the engine more slugish.

I had the 60K service at 70K so it is time for another one now that I am at 98K.

Even if I did a tune-up it really wouldn't effect the way it is running now would it? The rear o2 is bad so replacing that would make this all go away or what?

Anyone else?

When your engine is idling, is it rough? Irrattic? or smooth but low?

O2 sensors are supposedly made to last forever. They do not wear. But they will fail if something else in the chain (fuel delivery chain, that is) fails. Poor fuel delivery is most likely the cause of your O2 sensor going south. If you replace it now, you will burn that one up too. You need to find out what is causing your knock sensor to go off the chart and your 02 sensor to fry.

I'm my case, about a year ago, I had a rough idle and slight miss at driving speed. And the Cel light was getting more and more persistent, even started to blink at me while I was driving. I took my car in to get it checked out. They told me that it was an injector, most likely the #6 injector... and my O2 senesor was fried. I checked the codes, rear O2 sensor and faulty injector (I think). I went ahead and installed new injectors on the back bank. Cel light was off. I manually cleared the errors on the ECU. No new codes to date.

BTW: This happend to me when my car was right at 97K.

I've heard that some injectors on the max will wear out by this time. And that I should expect it.

I know that my errors were not exactly the same as yours, but if your rear O2 has failed, I would check the injectors. If you have a ohm meter, you can do this yourself.

If you want more info, let me know. I'll stop rambling now.

Later,
D

As far as I know, o2 sensors are considered maintenance items and
do eventually fail.

My idle is smooth and low(500rpm).The car seems to run quiet, but it seems as if it is too quiet, if you know what I mean.
So I should check the injectors before I replace anything?
If the ohm tester isn't too expensive I will buy one but if they are I will take it somewhere.

Even though my code said KS and rear o2 you think it could really be the injectors? Thank for the help

Change the o2 and your ks should go away.