And idler arm is more common on larger vehicles with a "parallelogram" steering linkage.
On our XJs/MJs, as well as YJs, TJs, ZJs, WJs, and such, a "y-link" steering is used. In a y-link, the drag link from the Pitman arm goes down to the (usually passenger) side of the tie rod between the wheels, making the whole thing look rather like a lower-case letter "y". No idler arm.
It's possible you've got a tie rod end on the drag link wearing loose - and they're fairly easy to check. The most advanced tool you'll need is a large pair of slipjoint pliers...
1) Jack up the front of the vehicle. You may do this by the axle housing if you wish, you just need to have the front wheels free of the ground.
2) Everywhere you see a tie rod end, grab the linkage to either side of it with your hands (the TRE should be between your hands.) Shake and twist the thing - there should be some resistance to twisting, but not much. You should not be able to easily shake the thing.
3) With the large pair of pliers, work your way across the linkage from wheel to wheel. What you'll want to do is compress each tie rod end, pressing the stud into the housing. Travel in should not be more than 1/16", and the joint should rebound fully (if it doesn't, either the stud is worn or the spring has had it.)
Total time? Takes about fifteen minutes or so. The compression test (with the pliers) can be done on the ground, but it's better if you have it in the air. Don't neglect the TRE at the Pitman arm on the steering box - with a y-link steering arrangement, that's the one that's usually under the most stress anyhow.
(NOTE - In a parallelogram steering linkage, the idler arm is found on the passenger side framerail, in a location that corresponds with the Pitman arm on the steering gear proper. The tie rod from the Pitman arm to the idler arm is called the "drag link," and "tie rods" from from the arms to the wheels.)
