Dictionary
If there isn't a word for "when you suddenly remember you have to do something and rush up/downstairs to do it, but by the time you get up/downstairs you have forgotten it completely", then there should be. As you can see, it is tedious enough explaining it, and I get this feeling so often that by the time I finish explaining it to someone, in all probability I will have forgotten to try and remember what it is I've forgotten, anyway. So anyway, let me propose a word for it. Elide. Eliding. That sounds OK. "So I was eliding yesterday, and...." Yes, that sounds fine. I would name it after myself, having been (as far as I know) the first person to want to coin a term for such an activity, but somehow "Rachelling" just sounds wrong.
There should also be a word for that bemused, semi-constipated look you get on your face when engaged in the abovementioned activity, as you stand at the bottom of the stairs, your features creased up in a look of unmitigated confusion, as the strain of recollecting what it is you wanted to do slowly but surely turns your brain into to a kind of wet porridge. I think I'll call it "norking". That sounds about right.
There should be a word for the godforsaken activity of slowly retracing your steps up and down the stairs in hope that going through the same motions will trigger a neuron somewhere, never mind that you look like a fool walking backwards down the stairs, norking. Immediately this word drifted into my head: "trollocking". It will do.
There should also be an adequately abrasive expletive for you to explode with, when you have elided and trollocked for half an hour, norking like a moron all the way, and cannot for the life of you remember what it is you wanted to do. I am no good at coming up with expletives. Do what you can with existing ones, or mail me/comment with inventions of your own and I'll test them out in the privacy of my own home, the next time I elide.
And finally, there should be a word for the kind of person who does this so often that they are compelled to coin terms for it. "Rachel" will do for this one, I think. My heartfelt condolences to all Rachels out there, who are doomed to spend their days eliding, trollocking and norking. I feel your pain.