Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.

See Figures 8 through 12

Jerking the right wheel assembly back and forth is not an acceptable testing procedure; there is no control on the amount of force being applied to the idler arm. Before suspecting idler arm shimmying complaints, check the wheels for imbalance, run-out, force variation and/or road surface irregularities.

Fig. Fig. 8: Checking the idler arm for wear or damage

Fig. Fig. 9: Using a back-up wrench and a ratchet and socket, remove the idler arm-to-frame nuts and bolts

Fig. Fig. 10: Remove the nut from the idler arm ball stud

Fig. Fig. 11: Use a suitable steering linkage to separate the relay rod from idler arm ...

Fig. Fig. 12: ... then remove the idler arm

See Figures 13 through 17

Fig. Fig. 13: Exploded view of the relay rod-2WD model shown

Fig. Fig. 14: Exploded view of the relay rod-4WD model shown

Fig. Fig. 15: Unfasten the relay rod-to-inner tie rod nuts

Fig. Fig. 16: Use a suitable puller to separate the relay rod from the inner tie rod

Fig. Fig. 17: Remove the relay rod from the vehicle

1. Clean and inspect the threads on the tie rod, the tie rod ends and the ball joints for damage, and replace them (if necessary). Inspect the ball joint seals for excessive wear, and replace them (if necessary).
2. Connect the relay rod to the idler arm. Use a steering linkage installer such as J-29193 (12mm), J-29194 (14mm) or equivalent (as applicable) to seat the relay rod-to-idler arm ball joint stud. Tighten the tool to 40 ft. lbs. (54 Nm), then remove the tool.
3. Install the idler arm-to-relay rod stud nut and tighten it to 35 ft. lbs. (47 Nm) on 2WD models or 60 ft. lbs. (82 Nm) on 4WD models.
4. Connect the pitman arm to the relay rod (make sure that the seal is on the stud). Use a steering linkage installer such as J-29193 (12mm), J-29194 (14mm) or equivalent (as applicable), install the correct one onto the ball stud and tighten it to 40 ft. lbs. (54 Nm) to seat the taper.
5. After seating, remove the tool, install the lockwasher and nut and tighten to 35 ft. lbs. (47 Nm) on 2WD models or 60 ft. lbs. (82 Nm) on 4WD models. A NEW nut MUST be installed.
6. If equipped, install the steering shock absorber.
7. Install the inner tie rods to the relay rod, then install the mounting nuts and tighten to specification. For details, please refer to the tie rod procedure located later in this section.
8. If removed, install the steering linkage and differential carrier shields.
9. Remove the jackstands and carefully lower the vehicle, then check the steering linkage for proper operation.