It would be a lot easier if people would post their solutions as opposed to just saying "problem solved"

The intro text and item title took me a while to find. I just updated to the latest K2 version and I lost all of my changes. I made them some time ago so I had to spend a bunch of time to source the code again.

So if you are also looking to change the article title size/face and your intro text go to:

/components/com_k2/css/k2.css

Look for these two lines:

For the article title:

div.itemHeader h2.itemTitle {font-family:Georgia, "Times New Roman", Times, serif;font-size:24px;font-weight:normal;line-height:110%;padding:10px 0 4px 0;margin:0;}

For the article intro text:

div.itemIntroText {color:#444;font-weight:normal;line-height:1.5;padding:4px 0 12px 0;}

The above are with my changes to the original. Much nicer looking. If I was K2 I would make that the default size because that bold intro text looks terrible.

UPDATE: Put the changes into your k2-override.css file in the css folder inside your template folder. Then you don't have to worry about your next K2 update screwing up your formatting. I've been experimenting a lot lately with the override.css file and it is a marvelous thing.