hey, I've fixed all my problems w/cold air and spark plugs. Now, I'm looking to upgrade the fuel system. I have found all the parts neccessary, except fuel injectors. Anybody know where I can find some for a 2000 Focus SE 4dr?

Fuel delivery is controlled by the PCM. Why bother?

you won't need to upgrade injectors unless your going the forced induction route or building your engine to be high compression. On a stock engine with bolt on mods, the stock injectors are fine. But, you can upgrade from ford racing. These guys also sell injectors, they are Accel, http://www.modernperformance.com/ford/onfocus.shtml
Hope this helps.