Jeep issued an emissions recall in late 2006 to update the powertrain control module (PCM) software on certain 1996 vehicles. As part of the recall, the catalytic converter will also be inspected for damage and replaced as necessary. To see if your vehicle is included in the recall you can visit the Jeep website (owners' section) that allows owners to input their VIN number and check the recalls on their vehicle.
Car Problem Reports
Jeep Grand Cherokee Emissions Recall Due to Catalytic Converter Failure
Jeep Grand Cherokee Problem
Exhaust & Emissions Affected: 4.0L 6 Cylinder
Average Mileage: 121,500 mi (120,000 mi - 123,000 mi)
Visitor, 1996 Jeep Grand Cherokee
Problem with a defective catalytic coverter.
Pcm "software" is actually a hardware issue, the ignition coil circuit to be exact. It can cause stalling backfiring due to the feeding of raw fuel into the exhaust. Catalytic converter was melted and ruined inside. Converter was removed, PCM was replaced with a functional reconditioned unit.