Hotmama,
Sour smelling clothes? Can't say I've ever had a problem. Although my bath towels can get a bit skunky if they're not hung up properly.
I think you're right that they're probably taking too long to dry. It's important to give each item enough space and whack it out good before hanging it up so all wrinkles and overlaps of fabric are removed. We often hang my dp's cotton long-sleeved shirts on hangers rather than directly on the rack because they hang better.
Also, if you can get your clothes up near the ceiling...that's where the air is the warmest. Of course, you can't beat a woodstove for great drying heat but not everyone is so lucky.