I had a very similar situation in my truck at about 65mph going up an incline on the freeway.. A light shudder under acceleration, usually more noticeable going up hills, Ended up being the torque converter shuddering under load. Just mentioned this in another post here tonight.

There is a cheap additive to add to your transmission fluid called "Shudder Guard". I added this to mine and it worked, the shuddering stopped. Good news but bad news too. If you add this and the shuddering stops the torque converter is beginning to fail. If your fluid is at the proper level but pretty old you could do a fluid change to a DEX VI transmission fluid add more shudder guard perhaps 2 bottles and squeak out a few thousand miles or more from your tranny. If when you do the the 1st shudder guard bottle for the experiment and you still have a shudder well it was at least a cheap experiment and your torque converter is good.


https://www.wynnsusa.com/product/shudderguard/

Torque Converter Shudder & Diagnosis

There are a lot of people who describe this as hitting a rough spot in the road. Often times the problem is a torque converter shudder. The torque converter shudder is a brief shake in the vehicle whenever the internal clutches apply inside of the torque converter. They call this a lock up. Often this issue is misdiagnosed and sometimes will end up with the transmission needing to be rebuilt.


If you’re searching for “What is torque converter shudder?“, you’ve likely experienced an issue when you’re driving around 45MPH and you get a sudden shudder in the vehicle. It is similar to running over a rough spot on the road or over a cattle guard. Just as quick as it happened, it is gone until it happens again. Read more about torque converter shudder in this post.