i have an 05 silverado 4.8 v8, and whenever i give it gas, it has a very fast paced rattling noise to it. not sure if its an exhaust leak or a headgasket or what. when im not giving it gas at all it wont rattle. only when i give it gas. if anyone could help me with this that would be awesome! thanks! (btw it has 150,000 miles on it)

 

I had something similar to this in my 08 silverado 4.8l. But it was in the intake side of things. Somewhere in the fender where the truck sucked in air. Never could figure out where it came from. Traded it in for another 08 silverado (6.0l)