what'd I break?
 

I was taking the cover off of the airbox housing to reoil my k&n filter and when I took it off, a yellow tube snapped that was attached to it. Can somebody tell me what this is? also if it's easy to be fixed and if it needs to fixed right away? I attached a picture showing what the tube looks like and where it broke off from.

The line you broke is the breather line/hose to the fuel pressure regulator. They do get brittle after time. You can go a while with it disconnected but, its best to not let impurities damage the regulator. You can pick up a foot or two of vacuum line from your Merc dealer or just run to your local hardware store to get some rubber tubing. Either way your not looking at a performance/economy problem with the line disconnected.
Good Luck!
Adam