hey all, i hear this weird sound, kind of like a howling/whistling sound under acceleration. it does not happen all of the time though, its an 07 base, automatic with almost 55k miles. an easy way to try to explain this is when moving real slow with the engine basically slowing itself down the howling sound the engine makes, its similar to what that sounds like under acceleration, yet its not all of the time, it stops under braking and when i take my foot off the gas. this has just started recently. if it was doing it all the time i think it would be easier to figure out, but due to it being intermittent this has me quite confused. any help would be appreciated, thanks!!