Whenever I start my car in the morning, it will idle fine for a couple of minutes, then it will begin to idle roughly while simultaneously a hissing noise will start to emanate from near or possibly under the throttle body. It will get louder and louder until the truck eventually shuts off. I've no idea what it could be.

Thanks in advance for any help.

 

You've got a vacuum leak of some kind. You probably should chase down that hissing sound and fix what's broken.

(Sorry, I can't reach through the video and triangulate exactly where it's hissing from.)

Due to the age, you may have gotten a plenum gasket failure; that's something to keep in mind.

RwP

 

I began looking and removed the throttle body; about a third of the throttle body gasket is missing. I'm hoping this will be my culprit as it it's a relatively quick fix.

 

That ... would do it.

Wonder where it went?

RwP

 

Likely the engine ingested, and burned it. It's just thin paper after all.

 

Update: replaced throttle body gasket after cleaning that and the IAC. Hissing noise still present. I really hope it's not the plenum.