Newer DIS (distributorless ignition system) 4.0L engines like used on 2001 and newer 4.0L engines are VERY picky about their spark plugs. Installing the wrong type of plugs... most notable single-tipped spark plugs like Autolite's AP-985 or Champion's 3034... will ultimately cause the engine to start running rough after a while.
DIS engines like in your '04 Rubcion run best and the longest with double-tipped platinum plugs like the Autolite APP-985 or Champion 7034. Or the Autolite XP-985 which is iridium tipped. Any of those three plugs will give you over 100K miles of very good performance.
You could also run the OE model spark plugs which are conventional plugs with no platinum coating. The only issue with them is you'll have to change them about 4x as often as the platinum or iridium spark plugs. The DIS ignition fires the spark plugs twice as often as normal so conventional plugs only last half as long as they do with conventional ignition systems. So if conventional plugs would normally last 25-30K miles, they'll maybe last 15K miles with the DIS ignition like your '04 has.
So for your Rubicon, I would definitely only use the dual-tipped platinum Champion 7034 or Autolite APP-985, or the iridium Autolite XP-985 and then you can forget about needing spark plugs for another 100K miles. Really.