Inconsistent playing comes from not having a plan for the moves you make with your body, and from not having a musical plan for every note you play.
It works one day, then the next day it doesn't, it works, it doesn't ...if this is your pattern, then you must develop a plan. Hope has no business in music. Hope is dangerous to the performer.
My suggestion is to develop a foundation of musical and technical priciples and ideas. Do you have some?
Let's see if you do...in playing the piano, what is the function of your shoulder? What is its purpose? If you don't know immediately, or if you had to think about it, you have no plan for your shoulder. You should be able to point to any part of your body and describe the musical and technical plan and function for that part. (my grandfather used to play the trumpet with one of his parts, but that's a different story).
Likewise, go to your music, close your eyes, and drop your finger randomly on the page. Now open your eyes. Do you know exactly what you want to do with that note/chord/scale musically? Do you instantly know how to acheive that with your body?
If you answered no to any of these questions, you are playing on automatic, hoping that things work out right from day to day. Develop a plan.
Robert Henry