metallic flavor in beer?

As a new home brewer this was one of my major problems. I just could not figure out how i was getting the metallic flavor in my beer. So i started a process of elimination, First my pot. I re oxidized my aluminum kettle not only by boiling water for 90 min., but by placing it in the oven for approximately six hours @ 450*. Yet on my next brew i still had a small hint of metallic flavoring.  I pitched i yeast at low temperatures and fermented my wort at 65-68*. I then remembered there was on thing that would be causing the flavor, my submersible wort chiller. I have a coper submersible chiller i made for about $25. I in fact did originally oxidize it, however every time I brewed I would leave it soaking in Starsan. After several minutes in Starsan it actually clean the oxidation layer from the chiller causing the off flavoring.  I placed the wort chiller in a pot and boiled it for approximately 60 min., and to my surprise no more metallic flavor! Some times we get carried away wondering about correct temperatures and proper sanitation that we for get the basic things.  Just remember that when you have a problem with your brewing system just take your time and have a good process of elimination to figure out.