I'll agree with others that 100% consistency is an unattainable goal, and professional musicians make mistakes all the time. That said, the two practiced methods that immediately come to mind are:
1) Chunking. While working up from a slow tempo is one great method for working on fast technical music, an alternative method for fast music is to go at full tempo as much as possible, but only a few notes at a time. You can pick a manageable number of notes (say, 4) and play those first 4 notes at tempo a few times. Then play notes 2-5 at tempo, then notes 3-6 at tempo, etc., etc.. By playing overlapping chunks like this, you build up a ton of muscle memory of each individual note change. By doing a few notes at time, you make it easy enough to play accurately and not practice in mistakes, but you're doing so at full tempo, which makes it a closer approximation of the real thing than slow practice does.
2) Mental practice/positive visualization. Visualize as much as you can (sound, touch, sight, even smell) of playing the music in your actual performance conditions. Research suggests your mind can't really tell the difference between visualized practice and actual practice, and you can see real technical improvement from mere visualization. Visualization practice was first used extensively in sports psychology before being adopted by musicians, and tons of musicians at the highest level use it. One of the first "aha!" moments of visualization is seeing that sometimes you may struggle to even visualize playing a certain tricky passage correctly. This almost certainly shows that you have a mental block getting in the way—once you address the self-doubt, the technique will often resolve itself.