Help! What is this sound?
 

I'm getting a humm/buzz coming from the engine compartment. It has only happened while driving. It happens under load (with my foot on the gas) and not(mostly when I'm slowing down and take my foot of the gas). It seems to create a slight surge in power when it is humming/buzzing. I can stop the noise by hitting the gas. It will continue until I hit the gas. I tried shifting into nuetral while moving to see if it would go away but it didn't. When on the brake at a light and it happens the truck wants to go. Tapping the gas pedal again makes it go away.

So why don't I just get out and check where it is coming from? Because it only does it while moving or stopped on the road at a light. To pull over usually requires me to step on the gas which stops the noise. And I haven't had the opportunity to coast over to the shoulder and stop.

Any help would be appreciated.
REDBUCK50

Raoul has the solution to your probelm
 

It wouldn't take you long to drive over to where Raoul lives. You can arrange to meet him this weekend. Have him ride on top of the engine while you drive. The screaming you hear indicates one of two things. He's found the problem or he's excited about all the bugs he's catching in his teeth...