Well, I have figured out that the abruptness and loudness comes from the air conditioner compressor cutting on. The idle DOES go up when the compressor cycles on, so I will assume the IACV is functioning. Would a worn belt cause this? Or is it just normal for the car to get loud, whiney, and shakey when the A/C cycles on and off? Does a fan cut on or off when the compressor comes on and off? I'm quite new to electric fans and four cylinder motors 
