Focus Central makes a throttle body for the 2003 5 speed. It's different than the 00-02 5 speed and/or 00-03 automatics.
I just talked to Focus Central and they have a new batch of 03 5 speed throttle bodies in stock. Available now in Blue, Red, Silver, and Black. Limited quantities available...
I have them on sale this week for $249 and FREE S&H. This week only! They will ship from Focus Central in California however, since I don't have any here at the moment...