So 'crazy temperatures' you are talking about are in fact exhaust temperatures, not coolant temperatures....
This back and forth is getting ridiculous, the OP is looking for some pointers on what could be causing his issue. All you have advised is that because you have not experienced any coolant over temperature issues, that it can simply not happen.
I'll stand by my original post, from the symptoms they are describing, it sounds like it is a head gasket failure. This is just my opinion, but head gasket failures can of course occur on any engine not just 1.8T's.