air temp will not stay constant unless on full cold or full hot. Is this the blend door problem?

 

That's what I have been reading, and I have read a few different blogs that show replacement. I have an 06 and from investigating the same issue, it looks like you have to remove the radio and the glovebox, coupled with some small open ended wrenches to get to it and fix it in about an hour. I'll let you know how mine goes!