[Gmecm] 2.5L 151 TBI'ed & Working Great, but...

[Aphelion79]

Ok, got the check engine light figured out... got my oil pressure sender 
figured out... only problem now is on startup it doesn't "fast idle"... 
can anyone explain to me why this would be and what I should check for 
(or how even works lol)...

    * Idle Air Control maybe?
    * Is there a sensor that would send info to the IAC that it needed
      to "fast idle" in the first place until the engine got "warmed up"?
    * Does it only fast idle in cold weather?

Those are the only things I can brainstorm about it ATM lol...

If it is some sort of sensor, how would I test them to see if they're 
working properly?