I'm driving a 2001 Pontiac Grand Prix GTP and sometimes when accelerating I get an extremely loud engine noise, almost as if it's being revved hard. After about 5 seconds it will subside and will SOMETIMES be followed by a loud crunching noise underneath the car. While I hear this noise boost is NOT activated and normally occurs around 20-35 mph and once it hits 35-40 mph is when it disappears. It also doesn't happen 100% of the time, I would estimate 1/4 times it will occur. Any help or thoughts would be greatly appreciated, I may just take it to the shop if need be.
