τοὺς γέροντας λιποῦσαι ἤκομεν σύμπαντας τοὺς ῥήτορας τοὺς κεκλοφότας δώρων γραψόμεναι.

[Jorsay]

Leaving the old men, we have come altogether indicting the public speakers, who have been stealing, for accepting gifts. 

I feel like I don't have this sentence quite right. 

[billberg23]

The formula δώρων γραφή, "indictment for bribes," may have been presented in the lesson that contains this exercise, Jorsay.  So the last part of the sentence would read, "to indict for bribes every one of (σύμπαντας) the public speakers who have been stealing."  Note that γραψόμεναι is a future middle participle, expressing purpose (as the future participle often does).

[vbd.]

It seems like you assumed "σύμπαντας" to modify the subject of your sentence, however that wouldn't be possible given that σύμπαντας is acc. It would have to have been "σύμπαντες" (nom.) in order to modify the subject. As became obvious from the translation Bill offered, it modifies τούς ρήτορας.