GMC Repair: 01 Chevy Express 5.7L V8, vacuum hoses, vacuum leak

Question
I need some help finding what I think is a vacuum leak that I probably created while fixing something else.  I had to replace a bad alternator & removed the air cleaner to gain access.  The alternator is working great, but after a road trip (380 miles), I hear a hissing sound from the air cleaner area.  It wasn't there before the repair so I assumed I made a mistake reinstalling the air cleaner.  I rechecked my work but couldn't find where I went wrong; no disconnected vacuum hoses or any apparent cracks in those; air cleaner clamps are tight.  If it helps, check engine light is NOT on, it also idles smoothly & idle speed seems normal; and it runs & drives fine.  To pinpoint this, would it be ok to spray carb cleaner into the air cleaner, or around the throttle body?  I'm reluctant as I'm concerned the spray could damage sensors, is this safe, or is there a better way to figure this out?  I'm also wondering if I have a bad TBI gasket; but I thought those caused a fast idle too.  Any input you could give me would be greatly appreciated!

Answer
Hi
I cannot think of anything either that could cause a hissing sound.
Spraying carb cleaner is OK, the amount you'll be sparying wont adversly effect any sensors. Just watch and dont spray around plugs and plug wires (obvisouly).
The Alternator itself MAY be the cause of the noise or maybe the belt?  If you have rear HVAC check the vacuum line that goes to the rear heat control valve located under the front A/C Accumulator.
Good Luck and follow back post, if needed.
Pawl