Okay so here's the deal. i have searched this whole site for my problem but can't seem to find anything so I'm asking for help now. My 2006 dts temp gauge was going up past its normal spot when i was idling or at a stop lights as i would pick up speed it would go back to normal temp. So i called my dad (he owns a mechanic shop) and he told me to change the thermostat, so i listened and did but now it overheats even worse! And it wont go back to normal when i start driving, i checked the purge line when i first started the car and coolant was flowing out of it as was some air and after it got to normal temp i checked it again and there was only steam coming out! I'mnot sure if that is normal or not? I also had the surge cap off when i did both of the purge line tests as i was trying to get air out of the system. I should also mention the the heater would blow hot and then all of a sudden stop blowing hot? What does this mean? Im studying to become a mechanic and i haven't taken engine cooling yet so I'm stumped...will take any help before i dump more money into the car.thanks!