I haven't seen anyone report on changing the diaphragm. So you'll have to tell us how it works out. I pulled my plugs and coils to look for reason for my cold start driveability issues. Nothing obviously wrong, no oil in plug wells or eccentric shaft sensor connector. Looks like you can change the CVV diaphragm w/o pulling the valve cover. Need a tool to pry up the cover. I think something like this will work.
2 Piece Flat Pry Bar Set