Update: it seems to be working now. I went through my entire contact list/calendar and deleted everything Facebook...all Facebook birthdays, all contact pictures, company names, etc. It was a daunting task. Activated wireless contact sync again and it looks like it's working. It duplicated a few more entries again, but once I cleaned those up, it synced my changes to my Yahoo contact list and I've been up and running all day. I've also made changes from my Yahoo list to test it out, and it does update my device. I'm not sure how long it takes for the update to take effect, but at least it's working.
Looks like Facebook was the culprit. One little freaking check box...what's weird is that unchecking the "connect with BlackBerry contacts application" doesn't undo anything...so really the only way that I found was to manually delete everything. None of the Facebook information was showing up in my Yahoo or Outlook contact list (even after a one-way sync), so I couldn't use a PC to quickly remove the items. Oh well.
It's also nice to have all of those stinking birthday reminders off my calendar too...