Originally Posted by jeepjones
Replace the cap, plugs and wires.
X2. I'd also ask for a premium distributor cap and rotor that use brass, not aluminum, contacts which last a LOT longer. For the ignition wires, there are a LOT of poor quality aftermarket ignition wire sets that will just cause more problems than you can believe. They pull apart at the first spark plug change, cause radio noise, etc. so I would go to the dealer and get a set of the OE ignition wires which are very high quality.
Three good long-lasting (>100K miles) spark plugs include the Champion 3034 or Autolite AP-985 (both of which are platinum coated), or if cost is no object go with the new Autolite XP-985 which is iridium coated fine-wire technology.
Edit: Oh wait, do you have an 02 with the 4.0L engine? If so, you don't have a distributor cap, rotor, or ignition wires. And you'd need Autolite APP-985 or Champion 7034 plugs instead of what was recommended in the previous sentence, or the Autolite XP-985. If you have an 02 with the 2.5L engine, the first recommendations are still good.