CCKen

NTK Sensors:

Upstream, 23151
Downstream, 23099

Rockauto has the best prices I think.

XJwonders

Thanks!

Other than o2 sensors, what possibly could be the culprits? So I can check them out at the same time

CCKen

Let's see...let me get out my crystal ball..

Are you sure you exhaust manifold is not cracked at all?

Cracked exhaust upstream of an O2S will make the O2S think the mixture is lean, and then the PCM is tricked into thinkng it should enrichen the mixture.

NFJ79

How many times have you calc your mpgs? Did you try resetting your PCM?

XJwonders

It has been one year and 1 month since I start calculating my mpgs and I'm doing it every time I fill up. I have pages filled up with all data.

Should I reset the PCM? Is it taking leads off battery and touching them together for 30 seconds?

As for manifold. When I took the downpipe off, I tried to visually inspect the collector tube on the manifold and it seems that there's no crack on it.

XJwonders

I just had time to do work on the jeep... I just cleaned all engine sensors' ground locations, using this site..

http://www.naxja.org/forum/showpost.php?p=245993828

I'm gonna drive it around for a while and see if it improves.