Will, sorry for late reply.
no, the lambda tower is the projection with the plug in the top that houses the adjustment screw for the big air valve in the top of the throttle body.
This throttle valve or valve is not connected to the accelerator pedal, but is moved down by the air being drawn around it. The actual throttle blade or valve is directly nuder it about 4 inches, and is totally controlled by the accelerator pedal cable and your right foot. Thats the adjustment I was referring to above.

Oh, IAC can certainly affect uneven idle speed if it is not functioning freely.
It's just a little rotating cylinder with a slot in one side, turned by a stepping motor.
A quick fix might be to pull the IAC unit off and spray it liberally with a cleaner or even WD40. I actually blast mine with WD40 and then drip a little oil on the rotator every couple of years; so far so good.

DG