Is there a way for me to search through my favorites for a specific image?

No at this point.

Search the tracker ( gelbooru.com/index.php?page=tracker&s=list ) to see if someone has requested this already, because I bet they did. I suppose bump it if you find one. If not, make a feature request.

Bump it? You mean just make a comment saying "bump"?

Use your imagination.

Just say you agree that it should be implemented, I donno.

Well, the main reason I want it is to remove a certain image from my favorites. Therefore, I would need to find the image in my favorites list because that is the only place with a "remove" button. I actually found the image, but because I can't find it in my favorites list, I can't remove it. Therefore, alternatively, I'm asking for a "remove from favorites" option on the image's sidebar to undo the favorite.

But how can you be sure it's favorited at all?

I confirmed it by clicking "Favorite" to be greeted by the message "Post already in your favorites".

Go to your favorites page.
You should see a URL that looks like:
http;//gelbooru.com/index.php?page=favorites&s=view&id=16766

Add the following script to the end of that URL:
=document.location=index.php?page=favorites&s=delete&id=xxxxxx

with the xxxxxx replaced with the id: number of the post you wish to delete from your favorites.
This number can be found on the post page for that image under "Statistics" or at the end of that post's URL.

For example:

http;//gelbooru.com/index.php?page=favorites&s=view&id=16766=document.location=index.php?page=favorites&s=delete&id=1031226

will remove post #1031226 from your favorites.

Edit: I replaced the ":" in the above URL examples with ";" to avoid shortening the link script.

Thanks.