Feigao 7L, Warrior 9920 + 12 GP 3300 cells = hot?

Hi,
I've got this setup (Feigao 7L, Warrior 9920 on 12 GP 3300 cells) in a 1:8 buggy.
I get controller temps above 80C° (176F) and motor temperatures of about 80C°.

I wouldn't worry too much about this if nothing strange happened but I regularly lost control over the car.
Throttle didn't work at all and steering seemed to work sometimes, but without real power. Wheels turned some degrees on ground, lifted up they turned pretty slow.
Servo: HiTec 5945MG.

Do you think the reason might be thermaling or might the Graupner XS-6 have some problems?

I think it's the controller though since the problem seems to occur after driving for a minute or two and then regularly. After a short amount of time (ranging from seconds to a minute) the car is drivable again.

Bye,
felix