Air leak noise on cold start?

2018 TOYOTA LANDCRUISER
100,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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2018LC200
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  • 1 POST
When I first start my car in the morning, I hear a hissing noise for 10-20 seconds then a pressure release sound (please see video). In addition to this the acceleration power is reduced, shifting is not smooth, idle RPMs appear high compared to before, and I occasionally have engine shake when idling.

I have had the throttle body cleaned and programed based on mechanics recommendation which seemed to provide some temporary improvement however the problem returned the following day.
Video (Click to enlarge)
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Feb 24, 2025 at 2:18 AM
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STRAILER
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Thanks for the video, this sounds like an air injection problem like the air switching valve is getting stuck, can you get a better idea of where the noise is coming from? I would remove the air switching valve and clean it to see if that helps, plus with the engine cover off you may be able to get a better idea of what is making the noise. We should run the codes as well, there might be something stored there.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Check out the images (below). Please let us know what happens.
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Feb 24, 2025 at 2:14 PM
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