I have a 2001 F150 4.6 liter V8 and for a while now I have had the humming vibration problem from intake like many of you. After doing some research and experimentation of my own I finally fixed the problem here's what worked for me... on top of the engine right next to intake manifold on the right side is the idle speed control module that's the one with an electrical plug and a hose going to it you will need to take it off it's simple 2 bolts that's it I cleaned it thoroughly with parts cleaner and let it dry then reinstalled it hooked everything back up went for a test drive no more hum and the old girl runs smoother and is a lot quicker off the line. Hope this helps you guys this may not work for you but it did work for me

 

Check post dates. You responded to a 16 year old post.

 

You never know who might be reading through old posts... Like I was... And they might come across my solution and it might help them. I do realize I was a little late to the party on this one haha

 

@ Junior, I took my silencer out of the stock intake tube and I don't that the humming problem. Little better throttle response and better merging on the freeway. Wanna try that WMS velocity tube, how do you guys like the tube?