Just bought a house. It had a sour smell in the basement when I looked at it, but I assumed that once the stuff in the basement was cleared out the smell would go, too. Basement is now clean, but sour smell is worse, if anything. Very strong, and can even be smelled on the first floor. Basement has never flooded. House was built in 1993. Basement contains freezer, washer, drying, water filter & softener system, furnace-- nothing unusual. Any help most appreciated!