The car is turbod and I have checked all vacuum lines and there aren't any major leaks. My boost gauge shows perfect vacuum (22 inHG). The problem is I remember changing the brake MC not too long ago. It was an Autozone one; do those things fail easily?

One weird thing was when I did have a vacuum leak (a plug fell out) and I was at 10 inHG at no throttle the brake pedal did hold pressure.

Thanks for any help/advice