One problem related to o2 sensor has been reported for the 1998 Jeep Grand Cherokee. The most recently reported issues are listed below.
As with many other posts, the vehicle just shut down while driving on the parkway. Pulled off the road put the car in park restarted , waited a minute drove another 20 miles home , no problem. This has happened before in the driveway, or just leaving the house but never on the road. Have replaced ignition switch, both O2 sensors distributor cap, rotor and wires. Fuel pressure is good . Don't expect a fix from Chrysler , there are many posts here and online with no fixes. Just thought I'd add my experience to the mix. Time for a new car!.