The best way to return back to the 2.2 Froyo (2.3 is G)ingerbread) is to go to the All Things Root sub-forum (scroll to bottom of V forum for link). Then go to the All Things Root Guide sticky/Guides/the guide on the ZV9 update.
This will return your phone to a bone stock 2.2 state with a stock recovery.
Note: Make sure you do the update twice (once in custom recovery, and once in stock recovery) or your phone will act all sorts of goofy.