You receive the error code 3194 because Apple now signs all the firmwares with a digital signature, a mathematical computing algorithmic for demonstrating the authenticity of a digital message or document. What you need to do is to modify the hosts file in your computer. Here is the instruction:

• locate the file "hosts" in the directory of  "C:\Windows\System32\drivers\etc\" 

• use notepad to open the "hosts" file

• at the end of file add a new line
  

74.208.10.249 gs.apple.com

to redirect requests for certificates for authenticity that iTunes will make to the Saurik server

• save  the file and try your restoration again

Sources:

[1] Downgrade iOS 4.0 to 3.1.3 iPhone Firmware 

[2] Restoring iPhone (The error 3194)