Great idea using a internal dowl or socket for extracting, but I would use penetrating oil while taping fitting lightly in order to loosen threads a little and allowing the oil to do its work before trying to remove. This would be my first approach before attempting other methods listed above. Would like to add, if using heat, I would heat the fitting and not the aluminum intake, because the steel fitting would expand slower than the intake expansion. The heat would transfer to the intake without damage.
