E150 4.9 liter overheating

I am kinda stumped, I have a 1991 E150 4.9 liter that is overheating. I changed the thermostat and it still over heated. Realized the water pump was bad so i change that. Still over heats. I have replaced the radiator and still after 20 minutes of idling it redlines. I am changing the Coolant Temp sensor today to see if that helps. Any body have a problem like this before? Have any ideas what would be next. Just a note my radiator overflow is just a milk jug.

Thanks in advanced for your help.

Does the electric coolant fans work?
Are you getting any heat from the heater?