Hi Pitched Whistle At Idle
 

Anyone have a similar issue, I have an 84 300zx, Non-turbo , at idle it sometimes has a very high pitched whistle, at 800 + rpm's it disappears. When the AC is on the car idles a bit faster, about 850, no noise. Its not a major issue, but it can be annoying. Any help, idea's or suggestions is always appreciated.
Also, on a slightly different noise the car makes, when I start the car cold, there is sometimes a rattle noise that lasts a few seconds, sounds like its coming from under the gauge cluster in the dash, maybe something to do with vacuum lines in the ac/heater control, kinda sounds a mini jackhammer ... if you can wrap your ears around that.
My Z is my baby, so I might be over reacting, but I'm a firm believer that your car talks to you, like any machine, when there's an odd or unusual noise I take notice.