If you've just got it, I would recommend replacing the CTS or coolant temperature sender, NOT to be confused with the gauge sender, which as said on 2wd is at front of head near the shiny silver pipe that goes behind the ex manifold to the rear, it has a single wire to it.
The CTS is at the rear of the head other side under the inlet manifold, if this is saying it is too cold it will raise the idle for a cold engine.
tabetha