humming sound from intake manifold

I have a 2002 ford f250 with a 5.8 liter engine it has almost 200000 miles and it runs great. there is a humming sound coming from the intake breather area. I have replaced the filter and looked for anything inside the tube and it is clean. A friend told me it could be the idle air motor?

I have changed the filter and cleaned the entire intake assemble, and it still makes the sound sometimes.