Touareg over heating and losing Anti Freeze on 2008 Volkswagen Touareg

Hi All,
Heres my issue with my 2008 Touareg. If I accelerate quickly the temp goes right up, but coming off the pedal it goes down to where it should be. Also its losing anti freeze I need to put half a can in a week. The truck has 90k miles on it. Any help would be greatly appreciated.

Asked by for the 2008 Volkswagen Touareg