Couple weeks ago i posted about a humming sound from my engine...Its louder sometimes more than others...usually after the truck has been running a lil while itll humm like hell at idle (stop light, drive through)..well today i went up to the mountains riding some trails...and it was humming, so i stoped and opend my hood....The hum is coming from the airbox, i placed my hand on it and it was vibrating like hell......It kinda sounds like it tring to suck air and its not getting any???

Could be the MAF i dont know, but at least im 90% sure thats what it is...

 

My friend's 97 does that. Not sure why.

 

bump..anybody know why this is ^^^