Stalling when cool outside?

2003 FORD TAURUS
210,000 MILES • 3.0L • V6 • 2WD • AUTOMATIC
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SESS
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New plugs, new fuel pump, new fuel filter, fully checked vacuum lines, alternator passed checks, new battery. When it is 90+ degrees outside the car starts just fine, run like a champ. No problems. When below 90 outside it will start and immediately shut off. If you put your foot into the accelerator when starting it will run till you release your foot, then die. This only happens when below 90 outside. No CEL, no pending codes. In 20 years never encountered a problem like this. Not easy to solve without a CEL.
Sep 1, 2022 at 1:45 PM
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STRAILER
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I would service the throttle bore and replace the idle air control valve, which is on the throttle body as well.

Here is a guide to help with instructions below to help you with the repair:

https://www.2carpros.com/articles/throttle-actuator-service

Check out the diagrams (below). Please let us know what happens.
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Sep 2, 2022 at 1:25 AM
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This has actually already been done. I forgot to mention it as it was late on my initial write up. The IACV was one of the first things I replaced since the old one was 20 years old. I am uploading a video of it trying to start during the night when it's roughly 80 outside. Once it passes 90 this afternoon, I will take another video of how easy it starts and stays running.
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Sep 2, 2022 at 1:45 AM
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Once the cabin reached 90 degrees, as stated in the first post, I was finally able to record video. The two videos attached are taken 6 hours apart. If it is below 90 degrees, especially in the cabin, it will not run. It is beyond perplexing as with no CEL it is hard to diagnose, and I have replaced so much already. Hoping having both videos can help.
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Sep 2, 2022 at 2:25 PM
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SESS
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Here is more information to add.
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Sep 3, 2022 at 4:13 AM
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STRAILER
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Thanks for the video and the data, I noticed on the last data pic the MAF sensor reading is close to 0 was this with the engine running? If so the MAF is bad, or you have a leak between the throttle body and MAF. Also, if this is not the case, I would swap out the engine coolant sensor, here is the location of both sensors so you can check it out. Check out the diagrams (below). Please let us know what happens.

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Sep 5, 2022 at 1:43 AM
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Yes, this was recorded live data while the engine was running. I had to wait till it warmed up outside for it to start and stay running. Will only do it when it goes past 90. It is strange the MAF has not triggered the CEL. I will look into this and get back to you as soon as I can. Heavy rains here at the moment.
Sep 5, 2022 at 1:49 AM
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STRAILER
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Sounds good, please send some of that water this way!
Sep 6, 2022 at 3:37 AM
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SESS
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No can do. I'm in Texas and we need it. xD I have ordered a new MAF and should be here in a few days. I honestly didn't notice how low that voltage was. I hope we can solve the problem. Fall is coming and since it won't start or run when it gets below 90 going to be a problem.
Sep 6, 2022 at 3:46 AM
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STRAILER
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Yep, good call, I saw how low your lakes are when I was there a few months ago. Let me know what happens with the new sensor.
Sep 7, 2022 at 4:44 AM
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I have finally gotten the engine coolant sensor and replaced it. It was OEM so I figured I would start there. The problem still persists. Going to replace the MAF next as advised. So frustrating not having a check engine light on to give me a code.
Sep 22, 2022 at 4:25 AM
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STRAILER
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Yep, it could be the PCM is going out but we need to start with the obvious first. Please let me know.
Sep 23, 2022 at 4:46 AM
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SESS
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Hello. Sorry for the late replies, money has been really tight. I replaced the MAF, and it still will not start and run-in cool weather. By cool I mean 85 and below. Not freezing cold. If it's above 85 it will start and run fine, no problems. I'm going to have to give up for now as money is getting way too tight. Will have to continue in Feb when I get my tax return. Thank you for all your help.
Oct 30, 2022 at 5:03 AM
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STRAILER
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Okay, it sounds like the engine coolant sensor is bad here is the location so you can check it out. Check out the images (below). Please let us know what happens.

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Oct 31, 2022 at 4:36 AM
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SESS
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That has already been replaced. It is in a response further up.
Oct 31, 2022 at 4:50 AM
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STRAILER
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Sorry about that, let's check for vacuum leaks when the engine is cold only.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

This guide can help as well:

https://www.2carpros.com/articles/stall-at-idle

Please go over this guide and report back.
Nov 1, 2022 at 4:32 AM
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Okay, I'll start there next time I can crank it and keep it running. It's currently in the 70's here. Until it gets at least 85 outside it will not start and stay running unless someone keeps their foot on the gas. Will have to get some help.
Nov 1, 2022 at 4:46 AM
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STRAILER
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Please let us know what you find. We are interested to see what it is.
Nov 2, 2022 at 7:54 AM
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Good morning. I would like to let you know the problem has been resolved finally. Replacing the fuel pressure regulator solved the problem. So, while some parts suggested weren't the issue, they were OEM so needed a replace anyway. Car is almost 20 years old. But it is now starting and running as she always did. Thank you for all the help. I will be sure to come here again if needed. This was a challenging problem with no CEL to guide the way.
Dec 9, 2022 at 2:49 PM
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STRAILER
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Good to hear, please use 2CarPros anytime we are here to help.
Dec 10, 2022 at 5:48 AM
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