I will definitely try unplugging the MAF sensor, I don't think it's a fuel filter or plugs, but the MAF sensor is worth a shot.
I would describe it as more of a squeal than a whistle. It actually sounded like I had a pulley seizing up, but I've since ruled that idea out. It produces the noise with or without the serpentine belt on the car.
Yes, it does idle rough due to the vacuum leak, but it runs absolutely perfect down the road when it has the leak.
If the vacuum leak (the drilled hole in the oil fill extension) is left untouched (i.e. it still has the leak) the car has no signs, symptoms, or other hints of anything other than the vacuum leak being wrong.
If you start it up with the leak it will obviously idle rough but as soon as you plug the hole it will produce this God-awful squeal for about 3 seconds, then it will go away and idle fine. Then if you unplug the hole it will (again) produce the same noise which also lasts for 3 or so seconds. After the 3 or so seconds it won't make the noise anymore, but will start to idle rough again due to the vacuum leak.
Just to make it perfectly clear, the car runs down the road PERFECT if the vacuum leak is left untouched. In fact, it will not produce the noise at ALL if the leak is left untouched from engine start to stop. With the leak unplugged, the ONLY thing that seems wrong with the car is the rough idle (which is caused by the vacuum leak of course). But if you plug the leak it turns into a whole different ballgame.
Anybody think it would help if I tried to get a video of the problem?
