Mike, if you're hearing that clicking, according to all I've been able to find out,, including talking to the chief mitsu mechanic in this area, it's time to get that plenum out of there. It's when you hear the clicking that the screws holding the butterfly are in real danger of backing out dropping into your intake at which point you are going to trash some cylinders. The rebuild or replacement of the motor is big money. Best to take care of this sooner than later.

Seer

89LS,90LS,91LS,91LS,95SR,89JeepGrandWagoneer,90JGW,91JGW,92JGW,93RangeRoverLWB,93RRLWB,94RRLWB,94RRLWB,95RRSWB; 90'Dodgezilla' 1-Ton Cummins4x4.