This clearly sounds like an IAC issue. The fact that you replaced it is a good first step but since you did that, it seems it has gone the other way and now has a low idle.
I have not had much success over the years with resetting the system but let's try it here. There is a reset procedure for the IAC and it can be done one of three ways. Two of them require a scan tool and most don't have one. The other is a battery disconnect. So take both terminals off the battery and touch them together. This is called a complete battery discharge. Then leave the battery unhooked for about 10 minutes.
Then when you hook the battery back up, start the engine and let it idle for a couple minutes but do not drive it. Then shut it off for a couple minutes and then go drive it and see if it is any different. The ECM does a relearn of the IAC every time the engine runs and then shuts off. It commands the IAC plate to the full closed position and then back to the desired location.
If this works, the IAC is just not calibrated. Let us know what happens and we can go from there.
After this we are going to need to search for a vacuum leak. Have you checked for codes? If not, we should do that as well. Thanks
Images (Click to make bigger)
SPONSORED LINKS
Tuesday, February 18th, 2020 AT 4:15 PM
