I have a 2008 Focus. Its a manual transmission and I took it to a local shop and had the drive belt and tensioner replaced along with brakes checked on front and rear. When I got it back from the shop, everyrhing was good and it ran way better than before. A week later, I start hearing humming coming from somehere. I can't pinpoint it. But it starts when I get up to 15 mph and get a louder when I get to 30/35 mph. The sound stops when I slow down and take a turn. And when I am stopped and at idle, there is no humming sound. I have even been in neutral and revved the engine with parking brake on and there is no sound. Please help me with advice! Any would be appreciated!