i am having the same issue, only mine started happening after i installed a needswings intake. it doesnt sound like it has happened to you, but mine check engine came on about the same time this started occurring. the code was for rich/lean mixtures, which would make me think it has something to do with the MAF being confused, however visually it appears to be fine and i am not willing to spend the money to buy a new one and find out. best of luck