[Rev]

At 1500 in park, the torque convertor is engaged too much. That may be why it drops 600 when put in gear. The idle is too high anyway. Will the car not idle any lower? Seems to me there's a vacuum leak or the idle mixture is too lean for some reason. With the butter flies open that much. the engine is into the "intermediate portion of the idle slot" and may even be drawing from the main jets.

Rev