What he said. Just make sure it's not a TPS or MAP.To quote from my 1988 Dakota 3.9 manual:
Steps 1 & 2 are on installation.
3) Start the vehicle and allow to run for two minutes.
4) Shut off vehicle, allow 60 seconds for the throttle kicker to fully engage.
5) Remove the wiring connector to the idle speed control actuator (the "throttle kicker")
6) Hook up a tachometer to the engine.
7) Start the vehicle and run the vehicle until engine is fully warm.
8) Adjust the extension screw on the throttle kicker until the RPM is within the specifications show:
Mileage (less than 100 miles) 3.9L Engine 2400-2500 RPM
Mileage (greater than 1000 miles) 3.9L Engine 2500-2600 RPM
9) Shut off vehicle.
10) Reconnect the throttle kicker connector.
And there you are!