I have a 1997 4.0L TJ that is running really rough.
Here's the run-down.
A couple of weeks ago I heard a rattling around the transfer-case. My MPH went to crap, like 97 miles to the tank! I also smelled exhaust while I was driving and eventually couldn't get the Jeep past 35 MPH.
After jumping on the forum, I determined it was the catalytic converter. I just sold my welder about a month ago, so it was obvious I was going to have to take it in.
I called some muffler shops and they wanted anywhere from $600-$800 to replace the cat. Finally, I limped it to JeepMasters in Austin, TX and they replaced the cat for about $220.
I drove it out of the shop this morning and have the SAME problem! It doesn't rattle anymore (obviously) but the symptoms still exist. I was able to run it for about 15 minutes before it started giving me problems. Once again, I pulled in to the driveway with a rough engine and a Jeep that wouldn't go past 40MPH. What the heck is this? Is it the O2 sensor(s)? Which one? The check engine light is NOT on... This is my daily driver - please help!