So when i bought my truck some tard had put green coolant in it. I had it flushed and re filled with motocraft gold about a month ago. They said it was good to go so i picked it up and took it home. The next morning i did not have any heat i went back over there and they put almost a gallon of fluid in it. I just figured it had air in it. well couple days later no heat again i ended up putting two gallons in it. then when it got to temp it overflowed It was good for a few weeks now at a idle it blows out cold but soon as you step on the gas it gets warm. This might be a stupid question but do diesels have thermostats? Anyone have any idea what could be up?