coolant dissaperance, engine problem

[NoHachi]

Dunno what the problem could be..but two observations:

I had the same coolant loss problem once in my civic..could never find a leak or anything. Turned out it was a leak at one hose connection that would only leak when fully heated and under pressure. By the time I slowed down and looked under the hood it would have ended. Check all rubber hoses and be especially attentive towards any white residue..might indicate steam/fluid loss.

My civic had the same symptoms as yours regarding temperature..hard to cool the car if you are losing pressure and fluid.