I don't have any backups or whatever. My phone isn't rooted. It updated to Gingerbread 2.3.3 OTA a couple of days ago, and I hate almost every change that it introduced.
Stock Froyo, I assume you mean Froyo with HTC Sense on top of it.
You would have to root your phone and then load a Froyo ROM.
See here for instructions to install custom rom: Modaco Froyo with Sense