I know that there are a few threads on this topic but most center around the fuel pumps. In my case both fuel pumps, fuel filter and connecting lines have been replaced by a qualified shop. as well as a general going over of all mechinicals. The issue is that after some driving, 15 minutes or so the fuel pump (not in-tank) begins to make an intermittent loud groaning noise. with longer drives the groan becomes constant. I notice the noise when stopped. not sure if its happens while driving due to general engine sound of driving. I replaced the barometric sensor, the one in the side panel behind passenger seat. the part was pulled from a spider, not new. my guess is that the groan must have something to do with the rather complicated vacuum system. regardless of the groaning noise the car runs great. one concern is that the fuel pump me be getting damaged, or possible other elements in the fuel system. once, when low on fuel, the fuel pump made the same groaning noise. seemed at that time the fuel pump was starved for fuel. after a fill up, no noise. the whole thing is rather frustrating.