Over heating

I changed the thermostat and water pump refilled and bled system I can get good heat out of it when I rev it up, at idle blows noticiably colder air. Drove vehicle about 30 miles blew water out and overheated. Refilled and drove 5 miles overheated again. Refilled rad then drove home stayed in opearting temp but had no heat, a couple times a faint feel of warm air but then would go away right away. There is constant stem and water droplets out of exhaust no white smoke and no smell of prestone out back end, pulled oil dipstick and oil cap no notice of prestone, any ideas would be helpful