Pull the plugs and see what they are wearing for deposits. if they are oil fouled and cruddy, that's the reason for your idle problems. This will clean up as you cruise at highway speeds. 1.5 quarts/1000 is excessive. Have the compression checked. If that's OK, it still could be an oil control ring or two. Best bet is valve seals need to be replaced. BTW what's the mileage??
2000 Dodge Grand Caravan SE