The horrible noise and humming were the result of the exhaust system not having been properly repaired. The muffler shop had just inserted a piece of rubber that subsequently melted, between the exhaust pipe and cross member. I just returned from the exhaust shop, where they properly repaired the exhaust. I even looked under the car and exhaust system now has about a 2" clear from the bottom of the car. My car felts and sounds great. Thank y'all for all of the help and suggestions.