Macbook Air charging inconsistently I read the related entries. My Mac Air  11" from 2011 was charging intermittently when plugged in and shutting off suddenly regardless of battery charge level or adapter connection. This problem has been going on for at least a month. I have improved the condition and isolated the possibilities.  SO Now:   

-I have reinstalled OSX 10.9 (this was updated for firmware etc)
-Virus Scanned and removed infected files
-cleaned magsafe and adapter connections
-replaced battery (which was working perfectly for months before this issue) it is still in very good condition.
-main disk has been cleaned out and has lots of space

After the cleanup and OSX reinstall this morning, sudden shutoffs seem to have stopped..  If I wiggle the adapter/Magsf connection it will switch its status on the menu bar.    The charging speed and efficiency are inconsistent... then on a hunch I plugged in a USB drive adjacent to the magsafe.  as soon as I did this the battery went into charging mode at what seemed like an average rate...  Magsafe area cooled off..  now after plugging and unplugging I have repeated similar result and my charge has reached 70%.  

My only conclusion is possibly a physical problem with the magsafe i/o board (Ac adapter is also new).

What does someone more experienced reckon?

I'd like to know if there is some more direct way to verify that it is the Magsafe board?  (I live in Japan and they don't want to touch anything because I changed the battery, regardless that I had no warranty left)  also I/o boards are about $90 here,  so I want to exhaust options...

Thanks!
i CHANGED THE io board.  it mostly fixed it.  I did some sys maintenance which further improved things.  Finally I realized that my original surmise was correct but that the power supply also hd  faulty cable.  now it runs like new..  mgsfe, as convenient as it seems..  has been  nightmare of cable replacement for me.