I have an idea as what is causing it, that partial e-mail is saved as a draft, but as gmail does not have different folder for drafts, it gets to the inbox and that e-mail is picked by the BIS server as a new e-mail and gets push to your blackberry. To stop it you may want to create a filter so you don't get e-mails you sent as new e-mails, you can look at the forum for those instructions
I deleted and re added the accounts but I'm still having the issue. This happens for all 3 of my gmail accounts. I also notice that it happens when it gets saved as a draft so I think it might have something to do with the IMAP draft box. any suggestions?