Here’s one for you guys

A while back I was getting a strange sound from what I believe to be the air intake, occasionally when I put my foot into it hard I was getting a hollow vacuum sound with a pitched sucking noise, I am unable to explain the noise. This was only happening here and there not vary often, I haven’t noticed anything in the last month or two but still wonder what it was,

I have a stock setup, I don’t think it was from the filter box but closer to the engine.
I thought maybe a vacuum hose or something wasn’t tightly attached but when I took a look under the hood I couldn’t find anything.

Any thoughts?

 

There should be a vacuum hose that attaches right after the filter, above the passenger exhaust manifold that runs behind the passenger head. Make sure this hose didn't come off, mine did once