I have over 155k miles on my 04 6 and my temperature control stays close to cold, even after I have been driving over an hour. This problem just started. Has anyone else had this problem and what could this be?

 

Could be as simple as low coolant, or a bad thermostat. Could be a blocked heater hose to the heater core. I suppose it could also be a blend door issue. I'd start by checking the coolant level and changing the thermostat.