my 2012 RL with around 60k miles on it seems to have developed a bit of a mild shudder or hesitation only when you apply light throttle and under light load, like say when you just slightly put more pedal pressure to maintain cruising speed while climbing a slight hill. It seems to do it at pretty much any speed, around town or on the highway. If you apply more gas, or enough for the tranny to kick down a gear, it goes away and acceleration is smooth. It reminds me of how an old Toyota of mine would do the same when the plugs or wires or distributor cap+rotor were bad, except the Toyota would do it with all acceleration (light or heavy). Or another way to describe it is kind of like a much more mild version of "lugging" a motor in too high a gear for the load. No codes or check lights coming on. I had the dealer check the plugs and they are fine. It kind of seems like it's more noticeable when the car is cold and it's colder weather outside, but it's also still there on warm days and after the car is fully warmed up, just maybe not quite as noticeable.

The only thing that comes to mind is I have switched up gas station brands in the last month or so (new rewards program on the credit card LOL), but I'm still only ever using 91 octane (highest you can get around here).

From a search I did on here, some of the 3.7 V6 in the TLs seem to report this and it could be the torque converter? Would this maybe also be it with the RL? I've had the car 2 years, and from day one I always found the shifting wasn't as smooth as my previous 06 RL, which I just chalked up to being a different tranny (6sp instead of 5) and motor. I did have the tranny and all diff fluids changed when I bought it 2 years ago (about 30k miles put on since then).