Rappers: Why is it so difficult translating Flow to Words?

I feel like somethimes i have a really sick flow. I usually mumble some gibberish stuff, but man i feel that. Once i kinda of internalize the flow, i try to write text to that. But every time i try to think of words, they doesnt seem to fit in the flow. It just...does not work. The next day, i forgot what the flow was and have to start over again. Is that something i struggle with or do you guys have the same problem?

All these tool for writing rap texts do not really help me, since i dont struggle with ryhmes. It is the translation of flow to text that i struggle with.