So...does it throw any CEL's? So there isn't a vacuum leak or anything? Normally the '04+ cars have issues with the throttle body gunking up since they are DBW and cause hard starts, sluggish issues, etc...I'd try that since it's free as long as you have some brake clean of sorts. Are all of your rubber "T"s dry rotted? You said its holding the correct amount of vacuum...which would be about -20 or so.