Maybe this had been answered but I really don't know what this is. Does anyone know if this hose is supposed to be hooked up to something? It draws a vacuum and the reason I found it was that it was making an odd noise. If it needs to be left alone, I'll leave it as is. It's a 1996 with the 4.9. Thanks for any help.

 

It's the fresh-air inlet to the 2ndry air filter, indicated just below center of this diagram:


(phone app link)

If you put all the truck's details into your signature, you won't have to re-post them with each question, and we won't have to ask or go back looking through your posts. Click this & read the caption:


(phone app link)