We're talking about different things then. I set the car
mechanically to idle just below target without any vems interaction. I used an air bypass built into the bosch three pin IAC while the valve had a closed window with the connector removed. I figured that way, the car cannot stall as mechanically it has enough air to keep it going without closed or open loop idle control. Then I set the ref curve, then pid=0, then tuned the pid. The tactic you are mentioning did not work for me in particular, the tuning of P until oscillation then dividing it by 2. My P number until oscillation was very small, so I instead went for the flattest waveform, then trimmed it with I and D. This three pin is a dual solenoid and reacts very fast, so I had to slow it waaaayy down with a lot of derivative gain. Here's a screenshot of the final outcome for stable idle in my application. I also noticed my idle motor, for some strange reason, liked settings that where divisible by 3.