#8 misfire is usually a result of a blown plenum gasket, and clogged or clogging cat and or cracked heads(valve seat), due to the extra heat from a clogged cat. Have you done anything about the plenum? If you have, add it to your sig.

 

I'll do that! I replaced the cat, THEN () did the plenum a bit later. So I am worried about the current condition of the cat. I did a compression test the other day (dry-wet) (130) with no change in the results. So yeah I'm most likely looking at valve issues..I don't have a compressor anymore so doing a leak down test is a problem. I'm not sure what I'm going to do next. Maybe JK or a reman from RA ($267)...Might ck shop $$ to fix what I got? Not sure?

 

I got lucky with my 98 and dumped a ton a Techron plus in the tank for a month or so and Seafoamed a couple times . Cleared the carbon off the valves. But I replaced the plenum first ,then the cat about a week later. Try "unscrewing" the precat o2 sensor form the pipe and see what it does. That will be a good indication if the cat is bad again.

 

Yeah I seafomed the oil, fuel and through the BB vac 2x and zero smoke both times which I thought was odd. I'm changing the rear diff oil in a bit. So after that I'll unscrew it NOT unplug it & see what happens..You have thoughts on the reman CH from rock?

 

CH ? Sorry I'm slow.

 

na, cylinder head..

 

Went back to OE plugs with no change...

 

Did you get your #8 cylinder misfire resolved? If so, was it a valve problem? Did you replace Heads? I've read several of your posts, but can't remember if you found a solution? #8 is giving me grief again.