I just wanted to share some knowledge with other owners. My 94 1rst gen. 3.9L was idling slow and rough after a tune-up (plugs, wires, cap, rotor and air filter). Local mechs. couldn't scan obd1 on Saturday so I was forced to trial and error my rough running and stalling Dakota. After trying throttle position sensor that I returned, I bought an idle air control valve. Problem solved ! Runs like it should at 255,000 miles. Good luck with yours

 

I recently replaced my plenum and all major gaskets on my Dakota a 94 3.9 2WD just like yours and I have had a bad surging problem and rough idle... I have a Haynes repair manual and I cannot find a idle air control valve.. I was going to try replacing that and was wondering if it may be called something else... Like an Idle Speed Control Actuator? Thanks in advance.

 

Have you gone over all the rubber vacuum fittings making sure they're not leaking? Just starting at the simple things

 

Corey the IAC is the sensor that goes into the back of the throttle body. You can clean it with the right cleaner and a brush. be gentle. For anyone who wants to you can get a Snap On MT2500 on ebay for about $300 that will do a lot including resetting your IAC.