Mitsubishi Repair Problems? Ask a Mechanic for Answers ASAP
Which vacuum line did you unhook that caused it to start normally?
Did this happen prior to cleaning the throttle body (and the cleaning was trying to correct this) or was the throttle body being cleaned for other reasons and this happened afterward/as a result?
Hmm. The thing here is that unhooking a vacuum line creates an unmetered air leak which should cause the idle to go up not down.
Did nothing happen noteworthy prior to this condition starting?
Do you know if the timing belt is overdue for replacement (speculating perhaps it jumped time)?