1997 Tacoma heat problems

Hello, I am having trouble with my Tacoma and the heat. I flushed the heater core this past weekend. Before I flushed it only the intake hose going into the firewall was warm. After both were warm. But the heat still was only putting out Luke warm heat. I replaced the thermostat tonight and added new coolant. I let it run for 15 min then took it for a drive. It was blowing cold air when it was idling and then when I drove it, it was a little warmer than Luke warm but as soon as I pulled into the drive way it went back to blowing cold air. Anything else I can do? Thank you!!!