Okay I have 54,600 miles on my '07. The yellow wrench light has been going on and off for the last 6 months or so. In the last two or three weeks the YW has been coming on more frequently and the car has, at lower speeds, missed, stuttered, shuddered, etc and then drove normally. I thought the brakes were wearing, hanging up, so I changed them. Mind you there were no unusual sounds coming from the brakes. The YW still persisted and I did further research and with the help of others here for codes was able to determine the blend door was malfunctioning. I read some where, don't remember where, that one of the symptoms is a loss of power and I attribute what I felt before to that now. However, with 54K on the first set of rotors and pads and winter coupled with going back and forth to Wisconsin I figured the brakes were due for a change so it worked out.

As a side note when doing the rear guide bolts the shocks' housing gets in the way and I used a 6in ball extension to get around the shock housing.