I have had a sputter that has driven me crazy for a while now. I looked several times through this forum and JF. The most common answer I got for a sputtering problem was spark related. I changed the spark plugs, wires, and coil quite some time ago, and that fixed the problem for a little while. It came back, and so I changed to performance iridium plugs. That fixed it for a while, but then again it started coming back. I wasn't very noticeable for a while, but it steadily got worse. I finally stumbled across a forum posting talking about the O2 sensor. The problem that other people were having because of a bad O2 sensor sounded like the symptoms I have been experiencing. It is an easy check to see if you have a bad O2 sensor. All you have to do is to find your O2 sensors, and follow the wires to where the sensor plugs into the wiring harness. Unplug one of the sensors and then crank your Jeep to see if the sputtering has gone away. If not, then plug the sensor back in, and unplug the other sensor from where it joins the harness. It seems like this is a common problem, but it took me forever to find out that it could be the O2 sensor, so I wanted to post this so that anyone having the same problems can find the solution easily.