Many thanks to casey_1. 4R40W tranny in my 2000 F150 would "jolt" when downshifting on grades or due to accelerating. I thought I might need a new trans, but casey_1 suggested completely replacing the fluid (and filter too). Did so, and trans shifts like new! Also, I posted requesting info about the plastic ****/shaft that was in the trans pan, and got 5 replies... all accurate and helpful (**** is only used for factory assy and can be discarded). You guys are the best!!!

 

It's funny how the pan "surprise" freaks everyone out. There has been many posts here about it.

 

I'm glad it worked for you. New fluid can work wonders!