I was driving home today from Youth Group...and I noticed my car has a fluttering sound to it. Its espcially noticable when you punch it, and let it run up about 1k rpms. It sound's like there is a flap in the manifold or something. There is also a metallic sounding flapping coming from underneath the hood.
It sound's like a WRX, but its never sounded like this before. And when I take it up to 4krpms or so(in 5th gear), it has the bubbly sound...like its running rich. I took it to Inline today, for John to adjust my v-afc cause I upped the boost from 5-8, and this afternoon is when I noticed it.

When it idles, it has a consistant rumble to it...like a V8.

What should I do?

Am I running rich?

Did a vaccum line come loose or something?

Is it the wastegate?

Should I be concerend? I'm gonna take it to Inline toomorrow and see what they say!

Thanks!
Spike