if you dont complete the idle learn it wont idle, make sure you have enough fuel and time to complete the idle self learn
make sure it idles correct whilst doing the self learn procedure, ie: if its hunting while learning it will be shagged and wont learn
make sure you dont drive or rev it while self learning.
note you will loose all injector, IGN, INJ, airflow, water temp, correction values. so be sure to note them down if you have diff injectors, cams, airflow meter etc.