New stang 2001gt owner, need some help

ezeebink said:

I just replaced the battery yesterday and the problem wasn’t occurring before.

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^^^THIS is likely your problem. Why? Because after a battery replacement the PCM must re-learn all of the IAC idle trim settings. It should be EXPECTED to have a poor idle right after a battery disconnect.

To speed up the re-learning. Allow the motor to idle for a full minute at full operating temperature. Repeat with the AC on.

I had a 1996 Mustang GT that was completely un-driveable after a battery disconnect. The idle re-learn procedure had to be done to just get it down the driveway after any repair.

Troubleshoot IAC idle problems 1996-2004

This is why it's so important to maintain the battery and charging system in tip top shape.

Howto perform charging system voltage drop test

I would let my car warm up almost all the way if it were me. Even here in florida when it gets 48 I let it get plenty warm. My Tacoma hardy goes until its warrm. Its got 350,000 miles. Some articles say its bad or not needed . Always runs better in closed loop.