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hey guys im new to this forums deal so i apologize for any misunderstanding that might occur throughout any of my posts.
The reason for this post is to see if there is any way someone can help me find a vac leak that i have been dealing with for about two months now. It sounds like its coming from underneath the intake mani. Its so frustrating to hear that crazy sucking noise while the car is cranked and a few seconds after i turn of the car, but not be able to locate it 100%. Any ideas on what it could be?? Or is there any website i can go to to find the vacuum system diagram... or maybe it could be a sensor or valve. idk

 
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Do you have an aftermarket intake? Does it affect how the car runs? My 01 makes a sucking sound when I shut it down but there is nothing wrong with it. It also does it at idle but I have an intake.

 
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IF you have a CAI or an open air breather (air filter box), or a leak or a hole in the big tube between the breather and the throttle body, or just a big air filter attached right to the throttle body, you WILL HEAR every bit of intake noise. Normal. (Fix any leaks in the tube though.)

Does the idle go up and down, up and down, AFTER the engine is warmed up?
If not, then it can't be a big leak but it might be a small one.
A big vacuum leak will make the engine surge at idle.

Get a spray can of carb and throttle cleaner (it HAS TO BE flammable!), spray it around in the area of the noise. If the idle changes in speed or in sound, then you hit the leak with the spray. I narrow it down that way.

 
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This really needs to be a sticky...I know I have typed it numerous times in the past week....

 
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if you need a diagram , the full service manual is available online. just google it.

 
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@GolNat,
I do not have an aftermarket intake... and b/c im no mechanical pro i try not to make any quick modifications to this car without researching first. I have learn to do so thanks to this forums! lol Afterall, this is my dd.

 
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to answer your question sir,
yes, my engine does begin to surge after the car is warm. I do want to mention the the car runs great as long as i dont get fast'n-furious with it. but i do notice a lose in power when going up hill or when i make a perfect shift.. it will studder all of the sudden and when i let go of the gas just a bit it will pick back up (if that makes sense). its hard to explain due to my inexperience in diagnos(ology) lol. but im going to try that carb cleaner deal in the mean time. thanks

 
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will-do thanks buddy

 
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I can't tell you what is happening for sure with the low power thing, needs some checking. Got any codes? Basic tune up stuff? I didn't go back and read the entire thread.

On the surge thing, you need to check the Fast Idle Thermo Valve that is attached to the bottom of the throttle body. (I assume this pic matches your engine.)

#13 controls the fast idle speed before the engine gets to operating temperature. It must have good coolant flow and get hot or else it stays open too long, or takes too long to come up to temperature. I see the hoses and the little hose fittings get clogged with garbage from the cooling system. This is a common cause of the surging. (It could also have internal problems, be stuck, etc.)
Also the IAC #17 must get hot at the same time since it has coolant flow (both valves on the same set of coolant hoses), and it must not be stuck. 17 is what the computer uses to control the idle speed after warmup.

Each of these valves uses an open port in the front opening of the throttle body. You can yank off the big air tube and wait for the engine to surge, and cover each port with your finger to see which one stops the surge. If the engine is hot, the FICV is supposed to be completely shut, zero airflow. Follow the passages with your eye, that should lead you to one valve or the other. (I THINK the rearmost hole goes to the IAC, the forward hole goes to the FICV.)

HTH