I know there are so many possibilities to this problem but I figured Id ask because its had to happen to someone. Yesterday I started to notice a vibrating in the pedal and hearing a vibrating noise in the dash on the passanger side. You really cant hear it when hood is popped but my motor is loud. You can hear it a little if you stick your head in the front passenger wheel well put it is heard best in th cab with doors shut and windows up. Ok It really doesnt do it when in park only when in gear and when the pedal is slightly pressed. It doesnt make the noise untill the pedal is touched and the more you slightly press the pedal the louder it gets. I couldnt find anything and I swear its coming from around the firewall. Any guesses? Performance isnt affected at all! Thanks!

 

I had a similar problem about a year ago. Took the entire dash apart trying to find the source. Turned out to be a metal clamp on a vacuum line. It was hitting the fire wall behind the engine cover. It nearly drove me nuts for about 6 weeks. A friend was looking under the hood one day and noticed it. Sometimes it helps to have an extra set of eyes and ears when your looking for a noise sources.

 

I figure it has to be a fuel line or vacum that shook lose or something. I had to bring the truck to the body shop the day I started to hear it so I wont be able to give it a good look through untill the weekend. Im hoping that it is magiclly gone when I pick it up! Thanks for the idea man!