Unexplainable Transmission Stutter... help?

Ah, ok then.
I suppose it's also possible the governor is hung up, but no upshift along with the shudder is a bad sign. (bet you wanted to hear that):D
With a shudder and no shift situation unless it's the wrong filter or installed wrong I'd expect junk in the fluid and a burned direct clutch.

All this has probably gone through your head multiple times already.

Yea I dont like bad signs. I'm just perplexed as to how it could be fine before taking the car apart and then not good when putting it back together, mind you on a part that even worked on. That's what doesn't make sense to me.