Low idle issue - Cold weather related

[Xiphos]

I am having a low idle situation ever since it started getting cold here. It started the morning where it hit 15 below (before this cold day, never had any issues, and idled at around 7-800), and my 86 4Runner started idling at 500rpms. It runs great and doesn't have any problems once it gets going, just at idle.

Only thing I recently changed was the oil to 5w30. Other than that, I haven't made any changes. What could be causing this low of an idle all the sudden because of cold temps?

Thanks!

I have an 86' 4runner btw.

[jetwhine]

Xiphos,

You might have a ECT sensor going bad. (Engine Coolant Temp Sensor)