YOU SAID:

he went to the store but after he bought the stuff, he passes out.

INTO JAPANESE

彼は店に行きました、しかし彼がものを買った後に、彼は亡くなりました。

BACK INTO ENGLISH

He went to the store, but after he bought one, he died.

INTO JAPANESE

彼はその店に行ったが、買った後に死んだ。

BACK INTO ENGLISH

He went to the store but died after buying it.

INTO JAPANESE

彼は店に行きましたが、それを買った後に亡くなりました。

BACK INTO ENGLISH

He went to the store but died after buying it.