Did Google Penalize Me?

Then I would say it still could have been personalized results. You don't even have to be logged into a Google account to get personalized results. It has just as much to do with recent browsing history as anything else.

It also could have been QDF.

The other thing it could have been was you had a few decent links and lost them, or they got weaker. This is one I had not thought of before, but would make a lot of sense. First, you were doing links mostly from forums and blog comments is what you said. Sometimes those links get moderated and removed later. Even days or weeks later depending on the management.

The other problem with those type of links is they get weaker over time (most of the time). There are a few things that contribute to this.

-The more links that appear on a page, the weaker every link is. So the more comments that appear with links the weaker your blog comment link is. On forums, the same thing. Every time that someone posts, there is usually a link to their profile, sometimes a signature link, and anything they may have linked to in their post content as well.

-Second, blog posts and forum threads often get pushed down the page as new posts are made or new threads are started. As they get pushed down the page, their link from their home page, category page, or main subforum page gets weaker and weaker. That makes every link on their page weaker too.

The exception to these is when a forum thread or blog post attracts links on their own. That doesn't happen often, but it can counteract the weakening of the links.

The link building methods you are using is pretty much like plugging your fingers in a dam. It is going to be a constant battle.