YOU SAID:

i want to do a breakfast

INTO JAPANESE

朝食を食べたい

BACK INTO ENGLISH

I'm going to have breakfast.

INTO JAPANESE

私は朝食を食べるつもりです。

BACK INTO ENGLISH

I'm going to eat breakfast.

INTO JAPANESE

私は朝食を食べるつもりです。

BACK INTO ENGLISH

I'm going to eat breakfast.