After pondering both Eliezer's post and your comments for a while, I concluded that you were right, and that my previous belief in epiphenomenalism was incoherent and confused. I have now renounced it, for which I thank you both.

Hmm. I tried to write a response, but then I noticed that I was confused. Let me think about that for a while.

Lots of memories are constructed and modified post hoc, sometimes confabulating about events that you cannot have witnessed, or that cannot have formed memories from. (Two famous examples: Memory of seeing both twin towers collapse one after the next as it happened (when it fact the latter was shown only after a large gap), memory of being born / being in the womb.)

I'm not positing that you can have causeless memories, but there is a large swath of evidence indicating that the causal experience does not have to match your memory of it.

As a thought experiment, imagine implanted memories. They do have a cause, but certainly their content need not mirror the causal event.

Well, you really wouldn't be able to remember qualia, but you'd be able to recall brain states that evoke the same qualia as the original events they recorded. In that sense, "to remember" means your brain enters states that are in some way similar to those of the moments of experience (and, in a world where qualia exist, these remembering-brain-states evoke qualia accordingly). So, although I still agree with other arguments agains epiphenomenalism, I don't think this one refutes it.

I have, on occasion, read really good books. As I read the descriptions of certain scenes, I imagined them occurring. I remember some of those scenes.

The scene, as I remembered it, is not a cause of my memory because the scene as I remember it did not occur. The memory was, rather, caused by a pattern of ink on paper. But I remember the scene, not the pattern of ink.