Hello all. I'm a new user and poster here. So have patience with me if this isn't in the right section.
I have this high pitched whistle or squeel that started about a month ago.
It doesn't do it at idle or when parked and revving the engine. It starts at about 45mph and above. When it starts to do it. And you press the gas it goes away until you level your speed out then it comes back. If you let off the gas completely it gets louder. And if you stop at a stop sign or on a country road and get our you can really hear it. However, it stops after about 30 seconds. I've tried the neutral trick while driving and even the empty road while in neutral and cutting the engine off. Still does it. I found a section of hose that was split and replaced it. That wasn't it. Any one familiar with this? I have a video I can email if someone finds themselves interested.
And I apologize if I'm walking on ground already covered

 

Sounds like you have a vacuum leak at the engine.
Make sure your intake manifold bolts are snug.