Airspeed is controlled by attitude and flightpath by power. Just get in a Piper Arrow and chop the power completely at 100 feet on final and you will find out. It glides like a brick with power off.
If u lowered the nose ie controlled flight path with elevator the aircraft would also go down like a brick.
The only way that IAS would be controlled by attitude is if power is fixed ie, in a glide descent or a full power climb.