There are a few sensors where I'd keep a spare in a cool dry place. Crank position, cam position, throttle position, MAP. You might also want a spare IAC (idle air control). The IAC can be cleaned, but if you can't get it back to normal you'll have idle issues. Because the O2 sensors are finicky and could put your jeep in a bad running state, you might want the NTK/NGK replacements (not BOSCH) on hand if you find long lead times an issue there. Depending on where the 2002 started life it could have 2 or 4 O2 sensors.
