Start the car and unplug the IAC valve. Does it stay running without surging ?
It could be a coolant temperature sensor. Have you checked that out ? The computer uses the IAC like a choke. ( kinda ). The most common way a computer controls the rpm is with the IAC. It's used in combination with variances in timing and fueling but I've found the IAC does just what it says. Controls the idle air. Now, your car shows lean before it shuts down and that could be from the idle air control valve opening all the way up to try and save the idle.
When cold the car is running in closed loop. It's depending on preset programming to make the car run based on temperature. When it hits a certain temperature it starts talking to all the other sensors. The o2 sensors aren't used when the engine is cold. If you have a bad o2 sensor or the harness is damaged it'll cause all types of issues. I had a car that surged and ran like crap until I found out the o2 sensor harness was grounding out to the k member.
I edited a lot of this post to make it a little simpler
It could be a coolant temperature sensor. Have you checked that out ? The computer uses the IAC like a choke. ( kinda ). The most common way a computer controls the rpm is with the IAC. It's used in combination with variances in timing and fueling but I've found the IAC does just what it says. Controls the idle air. Now, your car shows lean before it shuts down and that could be from the idle air control valve opening all the way up to try and save the idle.
When cold the car is running in closed loop. It's depending on preset programming to make the car run based on temperature. When it hits a certain temperature it starts talking to all the other sensors. The o2 sensors aren't used when the engine is cold. If you have a bad o2 sensor or the harness is damaged it'll cause all types of issues. I had a car that surged and ran like crap until I found out the o2 sensor harness was grounding out to the k member.
I edited a lot of this post to make it a little simpler
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