when I took it to the dealership (couldn't replicate the shudder that day) the tech reset the learning parameters for the tranny or something like that. It didn't do a thing.

This seems to be a common theme with people experiencing this problem..

40 - 45 mph, light accelerator, shudder/hesitation occurs. not so much an issue if you're heavy on the throttle all the time..I expect it's more of a nuisance for people like me with short commutes..

Interesting… by OCV, are you referring to Oil Control Valve for VVT? If yes, what filter screen did you clean..?

Yes, oil control valve. There is a filter screen at the top of the oil pipe where it enters the valve cover at the OCV.

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Can you give a bit more info on this? Any parts required to do the cleaning, steps etc?
Thanks,
X

It's pretty simple. Unscrew the bolt at the top of the oil tube, there should be a conical screen loosely fitted on the end of the bolt and it should come out with the bolt (mine both did). Pull the bolt out slowly and carefully. I used pb blaster to clean the screens. Put it back together and torque as specified. There are two washers which I re-used each time without issue, though the drawing says to replace each time. So be careful you don't let one fall out.

You will see right away if they are gummed up and restricting oil flow to the OCV. In my case, I knew they were because I had a cam shaft retard code after the hesitation started. I had some sludge build up, which I think was caused by a bad PCV valve and some long periods of idling in hot weather, but who knows. I cleaned the screens, gently cleaned the OCV's, and also cleaned each cam position sensor. My problem went away and I've been doing 5k oil changes ever since along with checking the PCV valve and also the OCV screens occasionally.

I believe all Toyota truck with the 5 speed transmission can have this issue. I owned a 08 FJ since new and had almost 200k miles on it before I sold it in 4 days! It did it once on me until I started doing a transmission pan drain and fill every 15k miles. I believe the transmission fluid is the issue. I just did it on my 18 4runner at 18k miles on it and it was almost brown in color instead of red. I only use Toyota WS transmission fluid. A transmission fluid pan drain and fill takes exactly 3.25 quarts.

I know this is a 3 year old post, but I am in the middle of a similar issue with my 2017 SR5 at 48,000 miles.
With light acceleration at 30 to 38 mph on local city streets the truck would start acting up with a judder or shutter. It felt like I was driving on a washboard Road.

Dealer diagnosed problem as faulty torque converter. After this diagnoses, I noticed this Issue would not show up when driving the transmission in “S”. It only showed up when driving in “D”.
Dealer is replacing torque converter under platinum warranty. I will post again after getting the vehicle back and driving it for a few weeks.

I would second the above. Mine does the same, 2017 w/57K and has always done a little funky shifting around 40MPH when light on the peddle as described. From the reviews I have read on the 4R, the shifting at 40mph logic could use some improvement.