replaced the thermostat and still no heat. van runs fine and water temp ok. any suggestion on what to look for now.

 

Heater core might by clog, try flushing it, or grab the 2 heater core hoses, and feel it's temperature. If one is hot and one is cold, it is probably clog. both should be hot.

Another possibility is the temperature Blend door inside the Dash is broken.