Q:

How to master lengthy Tatum-style runs when I hit a wall?

I've been trying to master a certain pattern for my improv that I like to call the Tatum-style descending pentatonic scale. Jazz greats like Tatum would often break into this extremely rapid descending pentatonic scale pattern that would end on the downbeat with the root of the next chord. 
For instance when moving from an FM9 to Bb7, they would perhaps finish the FM9 measure with a descending A G E D C A G E D C pattern, starting way in the top octaves and running down the length of the piano, ending on the downbeat of the next measure on a Bb.  Hopefully you all can make sense of what I'm talking about, it's a common jazz improv pattern.
My problem is that when I attempt to play these at tempo, I go fine for a couple octaves' worth, but then halfway down the piano I lose the pattern.  I've tried practicing at slow tempo, even breaking it down into achievable sizes like only one octave, then two octaves, then three octaves of the pattern, etc.  But try as I might, with all the practice, when it comes to doing the full run at tempo, it always collapses about midway.
I can do it slowly, and I can do it at tempo in small sections, like two or three octaves, but for the full pattern, it's like my fingers get ahead of my brain (or maybe vice versa) and I just can't nail it. 
Any suggestions? Do I just need to keep practicing? Is there something mentally I can do to keep my brain and fingers on the same page? Is there something technically that will help with accuracy?
Thanks in advance for any help you can give!

A:

I practice these kind of patterns by using different rhythms and a metronome. 
I usually get the best results by using a rhythmic pattern which does not have the same length as the note pattern, so that you get inversions and don't always get on the same finger. 
In this 5-note pattern, I suggest using one 8th note + two 16h notes or two 16th followed by one 8th. Start with a slow metronome and move up. The pause after the 8th not gives you time to think ahead and to place your fingers correctly. 

