Weird Noise

I am hearing a weird noise coming from the engine of my stang (Sounds like it is coming from around the throttle body). It sounds like a hissing noise( tsss tsss tsss ), like air would be leaking or something. It is a very broken noise and never really a constant sound. It will sound like tssssssss ts tsssssssssssss tssss. I have tried using carb spray to see if it bogged down the engine, and it did not. Therefore I don't believe it is an air leak. The sound gets even more intense when I give it a little gas. The hissing noise really picks up immediately after rpms lower. I am wondering if anyone has had a problem like this before, or does anybody know what this could be? My car is completely stock minus k&n filter. I brought it to a ford dealer and he said try and take apart and put the filter back together but I doubt that will be the problem.

Any advice is appreciated.

Thanks.

Wouldnt using the carb spray around the engine though tell? It didn't bog down the engine at all when i sprayed it around all the parts.

yes vacuum hoses are good, and when i had the ford mechanic look at it for a few minutes he said all connections looked good too.

yeah, but you never know what could be wrong if you dont try. nobody ever said nitpicking was bad. lol it just annoys the crap out of me even if i turn the radio up, becuase i know it is still there and it still bothers me if you know what i meen. and its loud enough that other people can hear too.