Erratic Idle on my 2.9 E.F.I.

Had this damn erratic idle for the longest time so I finally did a scan and came up with a code 13 (Idle speed motor or air bypass motor not controlling Idle properly) The only thing I could find was the air bypass valve on the upper intake. Would that be what's causing this or is there some sort of idle speed motor/air bypass motor not described in the Haynes manual. Id appreciate any help. Thanks

Its more then likely your idle air control valve or u have a vacume leak

Thanks for the reply. If it were a vacuum leak, what's the best way to locate the leak? I've heard using a hose held up to the ear works, but where exactly should I listen and would it be a very audible hissing or a faint one. thanks.

check all ur vacume hoses by hand and see if there cracked or dry rotted anywhere...i suggest taking um off and putting it in a bucket of water and blowing through it while corking the other end