Its possible that's all it is, but it also kind of sounds like the sun shell is failing. I would look online or ask around for a trustworthy tranny shop and have them look at it.

 

Is it truly shifting back and forth between 3 and 4, or are you in 4 and the torque converter is locking and unlocking? That is somewhat common; sometimes caused by a bad TCC solenoid. Other than the sluggishness, I had similar problems. Tranny flush and new filter fixed it. Never have figured out why.

 

It honestly feels like the torque converter keeps engaging and disengaging 4th. But would that also have difficulty engaging Reverse every once in a while? It's done that a couple times for me now. I'll put it in reverse and it acts like neutral, then I put it back in Park and back to Reverse and it pops right back in.

I really appreciate it

 

At the same time I had the TCC lockup issues, I had that same problem with reverse. Sometimes it would clank and try to "grab" reverse, but only when the tranny was cold. Also at that same time, I didn't realize that my input seal on the transfer case was letting tranny fluid into the transfer case. So my tranny fluid level was gradually dropping, which may have contributed to at least some of this. But I've never understood why, after 2 simple tranny fluid/filter changes (about 30k miles apart), everything suddenly started working perfectly. Has been for almost 3 years now.

 

K well mine doesn't even try to grab, it just disengages the park and does nothing, no grab no clank etc.