2002 rough idle at park or stop

[devilsdomain]

Ok I have rough idle at park or at a stop. Shakes. But runs good when driving normally.

Went to autozone for them to pull the check engine light codes: P0171
-Air/Gas mixture too lean

So far replaced the mass air flow sensor.

-might go ahead and change the hose from the intake to air filter.
-Also I kinda hear a hissing noise coming from the engine while idling.
was wondering if it might be a vaccum leak.

* heard something about a IAC Valve but want other opinions first. Thanks for your help.

[mrmikey]

Pretty much answered your own question. A lean system + a hissing noise points to a vacuum leak.
Get some WD-40 and carefully spray the area where you think it might be leaking, it'll rev up and smooth out a bit when you've found the leak. Look for cracked or dusconnected hoses too.
Notice I said carefully spray the WD-40 as it's flameable.....Mike

[toddler62]

find that hissing sound. good chance you'll find a vacuum hose came off