I have the same heat problem many of you have or do (no/low heat at idle and gets hotter as the engine RPMs go up) I've searched and read threads until I passed out....wait, that may not have been the reason
Regardless, heres a question and hopefully a tidbit to help others. I located the blend door actuator (I hope I called it the right thing). I can see the shaft turn (and step with the temp switch). My question is this....It turns 90* from cold to hot. Is this correct? If so, then I can rule out the blend door not operating. I know it needs to be aligned or zeroed but I would find it hard to believe it would since it just happened. Can anyone confirm the rotation being 90* from hot to cold? Thanks!