For folks who are new - this issue has been around since the 5th gen - really in some sense since the 3rd gen. There are a billion threads about this and how different people have resolved it. Toyota calls the condition "steering wheel flutter". The solution for the Lexus GX models was a firmer preload spring in the steering rack control valve that increases the rack's internal resistance to feedback - (think of it like adding a firmer steering dampener). it also applied to the Fj Cruiser and maybe the 4Runner for some years.
https://static.nhtsa.gov/odi/tsbs/2013/MC-10131942-9999.pdf
If you can do this in 4hrs - I'm impressed!
"Some vehicles may exhibit a steering flutter condition while driven at approximately 55 – 70 mph. In some cases, this concern is caused by a wheel imbalance or RFV (Radial Force Variation) that is out of range. If the tire and wheel assembly is satisfactory, a steering control valve preload spring is available to reduce the steering flutter felt through the steering wheel."
If this should be done and Toyota does nothing but wait for pissed off customers, they’re freakin’ idiots. This is my first Toyota at car #24, and I have to say the more I learn the more disgruntled I become. If there’s an issue address it.