YOU SAID:

i would say something but i don't know what

INTO JAPANESE

私は何かを言うだろうが私は何を知らない

BACK INTO ENGLISH

I will say something but I do not know what

INTO JAPANESE

私は何かを言うつもりだが私は何を知らない

BACK INTO ENGLISH

I am going to say something, but I do not know what

INTO JAPANESE

私は何かを言うつもりですが、私は何を知りません

BACK INTO ENGLISH

I am going to say something, but I do not know what