This has to have been told somewhere

Okay those of you who read sci fi, tell me the name of this book. There's no way this hasn't been written before. It's so fundamentally classic that I'm surprised I've given it a second thought.

Idea for a new story came to me on Friday (third of the week, actually, but I didn't write the other two down because they didn't seem like they had enough to flesh out to a full story). This one is about a person who uncovers a vast conspiracy. Robots are infiltrating humanity. What he sees as familiar coworkers are actually just cyborgs. When one malfunctions, he learns the truth and the chase is on. The robots are coming for him and he has to flee and find others who know the truth so he can save humanity!

Pretty standard stuff, yeah? In the end he discovers that they robots aren't coming after him to silence him but because he's a malfunctioning robot himself. In fact, there are no humans left. They died off a long time ago. He and those others he meets that "know the truth" are in fact all malfunctioning.

So there's no way someone else hasn't written this story. I don't read a lot of sci fi (I stick more to fantasy), so someone tell me the name of this novel so I don't invest the time to right it only to find out it's a novel by John Scalzi or something.