my b16 idles high, like 1500 rpm on warm-up then drops to 7-750, that is normal, but if it is idling up and down after warm up then look at the IACV. i'm not sure but on your rear car do you have a sevice connector that you have to "jump" before doing throttle adj, timing, etc. my si is obd2-b and i have to jump the service connector first, if not whatever i adjust the ecu overrides. check your timing too and make sure it's good, then adjust the idle. what year is your car/ecu, etc i'll look it up in my book to see if you have a service connector.