GTVert2000

My cars making a weird humming noise from the intake. It happens randomly about once or twice a day, when i begin accelerating, if my car hits 2800 rpm or higher, for some reason it will start this loud, but deep sounding hum. I pulled over one day when it was doing it really bad, and under the hood it seemed to be comming from the intake by the filter. I have a k&n air filter with my air silencer removed. I have had the silencer off since 2005 and never had a problem. At a dead stop, if its doing it it has actually jerked my car forward reving it up a bit. If im doing about 60mph and it does it, i give it a little bit of gas and let off, and it will go away. Ive noticed it only does it when its about 60 degrees or lower outside. Once again, ive driven through cold and winter for years before and never a problem. Can anyone help me?