I have a greaselike buildup around one of my primary injectors. It's black with a slight green tint. It was only around that injector.

What the hell is it?

 

Pic 2

 

Looks like your lower injector grommets are leaking. Pretty damn common, even if brand new. I use a larger O.D. viton replacement to take care of that crap ...

 

Sounds probable. Any reason why it would have a slight green tint to it?

 

I just noticed that I don't appear to have the plastic spacer. Could that cause leakage? If so, why only 1 injector?

 

That will defineatly hurt. The injectors will be placed at an awkard angle. Chances are you have the fuel rail not bolted down perfectly parrallel to the engine, causing one to be at such an angle to cause a slight leak. I hate the stock placement and mounting of the fuel injectors..