Need Help! High idle after pressing gas then slowly calms down. 2004 GT

wmburns said:

There must be 10,000 or more threads about a "hanging" idle similar to your description. An idle "hanging" around 1000-1200 RPMs and then dropping to a slow idle (500-600) is normal behavior. The behavior is designed in place for SMOG reasons as well making the hydro boost brakes work correctly.

IMO the issue is to separate "normal" behavior from abnormal. 1000-1200 RPMs is normal. 2000 RPMs are not.

If normal behavior then you could change every part in the engine bay and it would behavior will remain as the programming has been build into the PCM.

Troubleshoot IAC idle problems 1996-2004​

Troubleshoot IAC idle problems 1996-2004

Back to the basics. Check for blown fuses. Especially fuse F2.2 and F2.8 in the Central Junction Box (CJB 1999-2004 MY). Confirm key on power using a known good ground. 1999-2004 MY fuse panel schedule...

www.stangnet.com

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