I have a 2015 SR5 with roughly 106k miles on it. A handful of weeks ago, I took my 4Runner into the dealership for an oil change and brake job, and also opted to do the suggested 100k differential service and transmission fluid exchange.

Since having these completed, I have run into shuddering at lower mph between 30-40mph when lightly accelerating. This problem does not seem to occur when accelerating faster or at higher speeds. This issue was completely non-existent before completing the service and the 4Runner ran flawlessly.

I am not super mechanically inclined, at least not enough to determine what the issue could be. From what I have read, this could be related to the torque converter but I am not 100% sure and also not certain if it is even worth trying to repair if that is the case, or if replacing the entire transmission is the only reasonable option for longevity.

Did I screw myself here by doing the preventative maintenance and uncovered a hidden transmission issue? If so, what would be suggestions to go about fixing the issue and would it even be worth it as opposed to trading in the vehicle? I love the 4Runners for their reliability and look, had a 4th gen before this one for many years, and originally planned on driving this one for many more years as well.

You should start by checking the differential fluid levels. Also notify the dealership immediately or take it to a shop that specializes in transmission work. The diff fluids can be checked yourself easily then you can eliminate that as the issue. Plenty of youtube vids out there on diff fluid changes.

Perhaps the transmission fluid level is done wrong and is too low.
I had a similar shudder issue at 48,000 miles. After my Dealer changed the tranny fluid the shudder started. When driving in "D" at about 30 mph with low rpm and light throttle my 4runner suddenly felt like driving on washboard road. It only lasted a few seconds. Shifting into "N" seemed to stop the short shudder.
Dealer diagnosed as Torque Converter problem. Tried changing all tranny fluid. and did some kind of reflashing ECM. Did not solve shudder. Dealer got approval from Toyota to replace Torgue converter. After driving several weeks the shudder came back. Dealer then got approval for replacement of tranmission.
By then I was doing my own on line research.
My reading identified the shudder as a torque converter Flex Lock failure. Toyota has history for decades across many models for this Toyota Flex Lock problem. Seems inside the tranny valve body there is solenoid and valve that controls the lockup clutch inside the torque converter. When the lockup fails to release timely the clutch acts as a momentary brake. Driving in 4S seems to prevent the issue (by changing TC lockup parameters) and can be a way to help verify your problem. Hopefully this info can help you get to bottom of your issue. If I had to solve this problem on my own dime I would seek a tranny valve body refurbish.

Just wondering if this could be the well known (notorious) differential roller bearing problem?

One way to check, is that problem goes away in 4 wheel drive.

I have had this issue since it was new 2011 SR5.
At 13 years old and only 60k miles I'm not worried about it. Its Not My DD.

It Really feels like a tranny issue. Seems to happen when doing a rollingstop and accelerating through the intersection, it sutters kind of like the tranny didn't get time to down shift a gear to start from 1st.
If You find the root of the cause please post it here.

This has worked for me in the past for Torque converter shudder.

Amazon.com

The drain and fill process for the 5th gen's Aisin trans has a very specific process. It has to be slightly overfilled and then drained in a tight temp window of 104-113F (40-45C). There's a second drain with a stand pipe that sets the level. But the fluid needs to be in this specific temp range.

I bet the dealer screwed that up and just dumped the fluid and put back in a random amount. Probably too lazy or stupid to do it correctly.

The Toyota shop manual tells you exactly how to do it. There are online versions of it that you can download.

Well, the cow is out of the barn on the ATF change, but I recommend watching this video. You'll get plenty of takes on both sides of the argument, but when I discussed with my mechanic, he said he too would discourage me from changing the ATF. I don't know the right answer, but food for thought.

https://youtu.be/jJr30r6RRgw?si=nzX3y39auXUsfZwM

I'm not telling you what the cause is, but I can tell you I had this problem a few weeks ago. I have a 2002 SR5 with 102K miles and it started shuttering around 2k rpms while accelerating usually uphill around 50mph. I was perplexed as I took it for a test drive going those speeds and didn't feel a thing.

I thought it was a torque converter and decided to start attacking if from cheapest to most expensive.

I do need new tires and alignment, but also saving for that.

First, I checked the transmission fluid. Hot and cold. It was fine. No discoloration or burning smell.

I'm also not super mechanically inclined and had a friend help me change the plugs (OEM), wires and coils and also cleaned the throttle body.

Throttle body was gunked up AND one of my coils had a crack in the housing.

After, the engine ran smooth and the shutter was completely gone.

Good luck!

This exact thing happened to me. They left the fluid level too low. Mine, a 2016 SR5, needed almost 3/4 quart of fluid. Immediately fixed the issue and I have put 40k more miles with no problems.

It is strange to end up on the low side of fluid level. The greater risk is to over fill it. You fill it up while cold, set the level, then warm up the engine which expands the fluid level. Then you reset the level with the fluid warm by draining off the excess. Thus it is almost impossible to under fill it, unless it was just incompetence.

My guess is they never checked the fluid level, just put in what they thought
was the correct amount, there are several DIYers on this forum that don't check the level when they do a drain and filled they just put back in what they drained out never knowing if it was filled properly before they started, so I wouldn't put it past a dealer lube guy doing the same, they are usually the newest and lowest paid guys there!

Get a infrared thermometer, watch many videos on how to check the level, get it up to correct temp-open level check plug-go from there.

Any dealer that offers flushes is suspect and there is a good chance level was not set right. Don't keep driving it shuddering-it's not good.

The video craeg_the_kraken sent from the car care nut at 3:27 into it is what I suspect the problem is.

Thanks. Best information yet on this shuddering issue. You did your homework and delivered facts.

Where is the OP? Did this ever get resolved?