Engine surges when idling?

Hi,

The idle speed is controlled by an Idle Air Control Valve. This allows a metered amount of air to enter the engine while the throttle plate is completely closed (your foot is off the throttle). Additionally, this valve permits more air to enter when the engine is placed under a load. For example, if you turn the A/C on it will change the airflow to accommodate the added load and prevent the engine from stalling.

Oftentimes, these will start to fail or there could be a restriction chancing how it works. In that case, the idle speed can change, as you described. Take a look through this link. It gives a detailed description of the operation.

https://www.2carpros.com/articles/how-a-idle-air-control-valve-works

Next, here are two links to look through. The first one explains how to service one. Try this first. The second explains in general how one is replaced.

https://www.2carpros.com/articles/idle-air-control-valve-service

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

I did a little research for you. I found there was a technical service bulletin for this vehicle that pertains to problems with the IAC. It seems to specifically discuss the wiring to it. I attached pics below containing the TSB, pics, and directions for testing.

Additionally, the last pic shows the location.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.