PicklingError while Installing add-on

Question

I was given the task of upgrading a plone site from 3.1.7 to 4.0.3. I've successfully gotten the site upgraded, but now I'm trying to install collective.lineage and I get the following error:

Traceback (innermost last):
Module ZPublisher.Publish, line 135, in publish
Module Zope2.App.startup, line 291, in commit
Module transaction._manager, line 93, in commit
Module transaction._transaction, line 322, in commit
Module transaction._transaction, line 416, in _commitResources
Module ZODB.Connection, line 558, in commit
Module ZODB.Connection, line 606, in _commit
Module ZODB.Connection, line 640, in _store_objects
Module ZODB.serialize, line 422, in serialize
Module ZODB.serialize, line 431, in _dump
PicklingError: Can't pickle <class 'quills.app.portlets.quillslinks.IQuillsLinksPortlet'>: import of module quills.app.portlets.quillslinks failed

Quills was installed before the upgrade, but wasn't being utilized on the site so I uninstalled it while the site was still a 3.1.7 via the quickinstaller (I don't believe quills has an uninstall profile).

Additionally, this error doesn't effect all add-on's, i installed collective.redirect yesterday without incident.

Obviously Quills didn't uninstall cleanly, but honestly don't know where to start when fixing this.

Any help would be greatly appreciated.