Just had a chat with a friend who had the same problem in his 355. After having the rads re-cored, problem solved. Something about the fins.... can't remember exactly what he said though.
It's possible your radiator fins are blocked with debris and the cores may be partially clogged. Get those radiators redone and then check your water pump!
Hmmmmmmmmmm, that's a wierd one. The reason I say that is because the coolant flows away from the water pump. So I don't see how that could get stuck on top of the thermostat when the water flows away from it? The only thing I can guess that it is would be, an old clip from the top of a thermostat that was in the car from before. Some how it stayed in the sytem, and found its way back the the termostat. Either that or, something off of one of the coolant temp sensors, attached to the cross over pipe under the intake plenum?
