This happened to me. The fix , if your car is 2006 or older, is actually the mirror computer AND the mirror actuators. They updated the actuators midway through the 2006 model year to address the short in the mirror. As a result a new computer is needed also.
Check my posts for one on this...
I upgraded to the 8.2, but for ease of swapping and because the 8.2 didn't have e brakes, I just used my 8.0 axles, rotors, and ebrakes. If I put the 8.2 axles and rotors in, can I use the 8.0 ebrakes and calipers?
L-SB-0064-09
This is the tsb that I have saved on my computer. However, the description of the problem doesn't exactly match the symptoms you and I experienced. Updating to the new part numbers did fix my problem though.
Got into a bad situation on a test run. Entering a trail, the southbound signage indicated it was a jeep trail. After awhile it narrowed down and there was a lot of off camber, blind climbs, rocks and loss of traction. After the point of no return, the northbound signage indicated it was 60"...
Took advantage of the 20% off ebay sale a couple of months ago and purchased the updated rear drive shaft.
Installed it today.
Should be clunk free now.
I recall someone posting a video of the running board trim mod without first removing the board from the truck. The trimming was done on the truck and then the waste material was dropped away when the brackets were removed. The benefit was not breaking all those clips/pins behind the doors...
The most common source is the isolator from an fj cruiser. 4Runner should be the same.
I have a set of isolators I am willing to sell. Some fj springs as well or maybe some 2" icon springs