Answer:
I can run but not walk. Wherever I go, thought follows close behind.
What comes once in a minute, twice in a moment, but never in a thousand years?
It is a sound of empty, speak and it'll talk back plenty. But all the more you yack, you'll get the same words back.
I climb higher when hot, But beware my rage, I’ll kill with a breath, If I can escape my cage
By Moon or by Sun, I shall be found. Yet I am undone, if there's no light around
The warmer I am the fresher I am.