IAC a Choke?
I think not. The throttle place in the TB is completely closed at idle. The IAC is opened by the PCM a specific amount to allow intake air to bypass the closed TP. There is also an adjustment in the TB housing to "fine tune" the bypass air stream in order to achieve the best idle and deceleration characteristics. A choke on the other hand, shunts off air to a carburetor, and richen the air fuel mixture. Thereby making an engine easier to start. For fuel injection cars, during startup, the injectors inject excess fuel just like a choke would, but is controlled by the PCM. Usually, once the O2 sensors are at operating temperature, the fuel mixture is adjusted accordingly, and the richness upon startup switches to the proper air/fuel mixture. The IAC and the injectors work together to that end, and are controlled by the PCM. Further adjustments will be made to the A/F ratio as the engine warms up and reaches OT. The MAF sensor and TB work together above idle. The base voltage readings of these are used to set them both in "range" of one another, and to work best when accelerating, and WOT. Although, WOT is a separate function of the PCM, having the proper "scale" on the MAF, and the TPS allows the proper timing for this pre-programed function of WOT. Basically, a smooth transition from sensor data to pre-programed operation. Hence, hesitation in acceleration are usually due to a problem with one or both the MAF or the TPS. This of course is not accounting for ignition problems, that can also cause poor acceleration, as well as a poor idle.