My truck runs cold?

[MfBox]

I just bought a 1969 c10 from arizona and drove it back to colorado. It has a lq4 6.0 Ls with a 4l80e trans. It has old air A/C and heat. When i start the truck in the cold it has a rough idle and even died a few times. Also unless i sit in heavy traffic the heater never really gets hot more like luke warm. Any ideas why this would be?

[geezer#99]

What thermostat?
What fan?
Is the motor stock or modified?
Are the heater hoses hooked up right?

[MfBox]

Originally Posted by geezer#99

What thermostat?
What fan?
Is the motor stock or modified?
Are the heater hoses hooked up right?

Not sure on the thermostat. It has ron fellows electric fans, engine is 100%stock right now. Came put of a 2500 silverado. The heater hoses seem to be hooked up correctly because the heat does work under certain conditions.