I own a 97 STS and I just had the fuel pump replaced. I don't know if the fuel pump has anything to do with it.. but I have a hissing sound inside my car now, and not only that, every-once-in-a-while, I have a really loud vibration and it sounds as if it's under my shifter... does anyone know what this might be...

i have a 96 sls an i had somthin like that goin on for about a week.i thought it was somthin under my car,it turned out to be my rear vent for the back of the car.under the middle cig lighter in the back.try switchin the levels,or turn it off.i dont know if its your problem but i thought id put that out there to ya.