Help identifying source of noise please!

About a week ago I noticed my truck making a hissing noise. When I turn the engine off the hissing continues for a few seconds then stops. Today the truck started missing and running rough for a minute. Cleared up and I drove it 5 minutes to home. All the hoses that I can see look connected. Jiggled every hose I could find and cant find anything. Noise seems to be around back of intake on drivers side. Any ideas where it is coming from? Thanks! 2001 4.7l

Short video with noise.
https://streamable.com/ukidgj

 

Welcome to the forum. Any trouble codes?

 

Intake gasket. @bmf4069 can confirm, he's had this happen a couple times now. ONLY USE either Fel-Pro or OEM on the replacement. You only need the lower gaskets. Don't make bmf4069 hunt down all the threads of his aftermarket shit gaskets he used, then had to replace because they blew out (he has pics, there's a reason he had to do it multiple times)

They are keyed to go a certain way. I have no doubts someone on here can actually show how they're keyed. Someone recently did this on his earlier-year, maybe I can find it. The later years have a formed rubber gasket.

 

This. White tab goes up IIRC

 

Thanks, @bfunke that helped me find the thread. @jdavis1 this guy gets into the intake gasket stuff and will outline how they need to be changed: https://www.tundras.com/threads/so-i’m-halfway-thru-changing-my-2001-4-7-starter-and-have-some-issues.143777/

Oh and I'll save BMF the effort since it's right in that post:

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To diagnose intake leak, get a propane grill light. Squeeze the trigger but extinguish the flame and probe around the intake with engine idling. If it speeds up you have a vacuum leak.

 

Can use a can brake clean or starter fluid as well.

 

I've seen Eric the car guy using brake clean to find leaks. Works well.

 

Thanks a lot guys. I'll follow up when I have some more information. Thanks.

 

The noise in the video is from a bad break booster. All the unmetered air was causing the missfires.