I ran the valvoline synthetic max life ATF stuff, and flushed it twice with the cheapest WallMart version first. Not sure what the local shop I used put in there, but they said they used some kind of solvent first and an additive in the ATF fluid last.

I drove it today and it did pretty good. Only noticed the shudder a couple times for only a second or two. I'm gonna drive it all week and see if it gets any better/worst.