dealing with inconsistancy

day oneplaying really well (for my level), goes up 100+ points,

day twomaking lots of silly mistakes(for my level), looses a load of points , what makes me sad.

this is always what seems to happen and has been like it for several years, i really feel like the reason i am not ranking up is because of inconsistant play from one  session to the next..

i would like to ask does (or has) others suffered with this issue and if so, how to overcome it.

im not really asking about improving, more so how to keep playing decent, instead of reverting to playing like total dead brain every other day.  thanks.

Perhaps you can use your irregular past performances to examine what external factors degrade your game. Were you too tired, distracted, or was it in the wrong time of day? Myself I need to make sure that I don't start playing chess after I come home from drinking at the bar.