Pull down kitchen faucet. When I turn on the water (cold), there is a sour rag smell. It goes away after a few seconds. It's only the kitchen. The faucet has been installed for over a year and just started a month or so ago. Have removed the head, cleaned it, checked the filter and there is nothing in it. What is causing this odor and how can I eliminate it?

Sounds like bacteria in the hose. You can fill it with bleach and let it set or simply replace the hose, Good luck, Tom