For ATS to appear hot on startup assuming it's not over 150 degrees or so under the hood at startup it would indicate a short in the air sensor temp. circuit.

Most chips don't use that information sent to the ECM so I'm not sure how that affected the idle, depends on the chip most likely or other factors.

I'd check the sensor and connector ends and wiring first.

An open or intermittant connection in that circuit to the ECM, would appear as dashes or cold temps. indicated.