iTunes error 3014 when restoring iPhone 4 (and your previous iPhone was JB)-Solution
OK, maybe this is posted somewhere, or it's common knowledge, but I've been pulling my hair out for hours trying to restore my iPhone 4 as new after initially restoring it from a backup (3GS jailbroken). I needed some data from my apps on my iPhone 4, so I first activated the phone with the backup--no problem. But then I wanted to start 'fresh', so I restored as new, and so began multiple hours of frustrating troubleshooting.
I kept getting iTunes error 3014 right at the end of the firmware installation on the phone, so I spent hours troubleshooting using what I found on Apple's site and on the web. The last thing I tried, and the ultimate solution for me was to go into the hosts file (C:\WINDOWS\system32\drivers\etc\hosts-open with Notepad) and delete the 22.214.171.124 gs.apple.com IP address-Saurik's server (IIRC, added to enable restore of 3GS after jailbreaking). I thought I'd have to hunt down another gs.apple.com IP address and write it in place of Saurik's IP address, or that iTunes would write it, but neither occurred, and my iPhone 4 restored to new without a problem after deleting that IP address and saving the file.
I hope this helps, and saves someone else the frustrating time I had.