Sometimes when my car is cold (and the weather's cold) my car will stumble really bad, acceleration sucks, the whole thing shakes, feels like it could be missing. When the car gets a little warmer, this goes away.

Now, it doesn't do this every time I start my car on a cold day, just randomly. Any suggestions to be thrown out there? I don't have a clue where to start on something like this.

New EGR, no vacuum leaks, new (well.. not NEW new, but not old enough to need to be replaced) fuel filter, my car's running too rich because of a damaged fuel pressure regulator (don't ask), and the wiring connector on the IAC is messed up, so I know that's causing some issues too.