I have a theory on the idle issue. I've had the problem for a while and I think it might have something to do with the electrical system. This is why:
The car only does it when I'm sitting in traffic after the car is warmed up. I've also noticed that it seems to be tied to when the radiator fans come on, which is why it waits until the car has stopped moving (there is no air pushing past the radiator, the coolant temp goes up, so the fans kick on). The radiator fans kicking on also seems to affect everything electrical in my car. Also, when you are sitting there idling a lot, the alternator isn't giving as much charge. Maybe the draw from the fans temporarily drops the voltage going to the IACV and/or the coil packs enough to cause poor combustion. So the ECU sees the RPM's drop and compensates with more/less fuel.
It's just an idea, and I'll find out soon enough. I bought a voltage stabilizer and will be getting an Optima redtop. If that doesn't take care of it, then we can rule that out.