I have a 2006 Grand Prix.. my car has been great until it started making this loud humming like sound.. not a squeel sound. and it's only when I accelerate, but when I take my foot off the gas it stops making the noise. The faster I go the louder it gets.. until i'm on the highway and then I don't hear it anymore. It is very annoying. Can you give me advice before I take it in again.. one place said I needed new tires and brakes...which were replace last year.. and i know that isn't whats wrong.. he tried to take me for a fool. Help...![]()