Also a dying battery would cause it believe it or not. Your ICV and other component's including the MAF have a 12 volt going into them from the battery. A weak battery which is losing a charge after sitting for a while would cause your equipment like the ICV to not power up properly right away. Don't believe me? Unplug your battery and plug it back in and I guarantee your idle will be weird. This is because the ICV and MAF take time to adjust. This goes for everyone with an e36 :P