Not sure on the 5.9 but on the 4.0 you can just loosen the nuts at the header flange and let the exhaust hang a bit. Take it for a short test drive and if your power comes back it's probably the cat. The three bad cats I've seen were all sudden failures. One melt down on a GM car and two Jeeps where the front honeycomb fell apart and lodged against the rear catalyst. Welded in universal cats; one has about three years on it and the other about two with no additional failures.
If you have a welder and the skill to use it it's easier to cut the pipe in front of the cat to inspect the catalyst and reweld it than to try and fill 1/2" holes with weld. If the cat is plugged you're going to have to cut it out anyway.
Once i get a chance to get to the muffler shop im going to throw a new exhaust on it, and replace the cat, the cat was rattling really bad, not any more however, witch makes me suspect the cat is damaged and/or clogged. I did not go through any water with the jeep so i guess that's out of the question. The same thing happened on another vehicle of mine, (same symptoms as my jeep, and it was a clogged cat.) Im also going to look into the misfire, as i need to give the 5.9 a tune up any ways, ill keep you guys posted when i have more info. Thanks for the help!
A plugged cat will cause a misfire. Fix the exhaust first then see what else is going on.
Doesn't need to be water to damage the cat, I rarely see that happen, But often see damage from rocks and stumps
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.
If you're going to replace the whole exhaust think I'd be doing it myself instead of going to some rip-off muffler shop. It's easy enough to remove the whole exhaust with just 2-3 cuts of a sawz-all or a torch if you have one. Then you can buy the higher quality parts you want depending on the sound/flow you're looking for. Plenty of threads around here on exhausts. If you want it welded together then clamp it temporarily and take it to a shop or better yet find a friend with a welder. You'll still be saving $ and be much happier with a higher quality exhaust. Good luck.
Yes, took it to the exhaust shop today, picking it up in a couple hours. The guy at the exhaust shop within 2 mins said the cat was bad, so i put a aftermarket muffler and a new cat on. Ill be driving it shortly, so I am pretty sure the cat failed. Sorry for the late reply, the jeep is not my daily driver. If the cat is not the problem I will let you guys know!