Bought this car and it wasn't running at the time. Replaced the main relay and it started up but it was idling really low. Checked the idle air control valve (iacv) and it looked clean, I cleaned out egr valves, and the fast idle thermo valve (fitv) was loose and dirty so I replaced that to try to fix the issue. While the idle did smooth out it was still idling around 500 rpm. Sometime after doing all that a whistling noise started to sound. It's not high pitched like a vacuum leak and it disappears after 550 rpm. I've also sprayed carb cleaner around the general area I thought the noise was coming from and I couldn't find any leaks. The noise sounds like it's coming from under the intake manifold but I can't seem to find a specific place it's coming from. I believe what ever is causing this noise is also what's causing the rpm to be so low but I'm not totally sure. I appreciate any help and will do my best to answer questions.

 

Look into how to adjust base idle if everything else looks right. That whistle noise might just be the idle air adjust screw on the throttle body. Mine does the same thing with the noise. But it idles correctly.