I need sources of interrogative, exclamatory, and imperative sentences
I ultimately settled on Gutenberg Project as a source of massive amounts of data. I realized that books (fiction and non-fiction) cover pretty much every permutation of human communication that can be represented in plain text. I've written a couple of scripts to parse Gutenberg text files and next I'll be working on a support vector machine to classify each passage as regular content or other (such as headers, titles, etc). 

https://www.gutenberg.org/wiki/Gutenberg:Information_About_Robot_Access_to_our_Pages