Your fault.
My daily machine is a mid-2011 MacBook Air and it works like a dream.
My old machine was a late-2007 MacBook Pro. It's logic board started acting up about a year after I bought it. I didn't buy AppleCare. Apple fixed it out of warranty at no cost to me.
Take it in. Apple will most likely fix it. Most likely at no cost to you. The machine has been acting up for a year. You chose to write a whiny blog post rather than take the machine in. That's your fault.