You've already diagnosed the clutch as bad. Freewheeling on shutdown is a classic symptom of a bad clutch, even when ice cold it shouldn't freewheel. A bad clutch won't transmit power to the fan to actively draw air through the radiator. If the coolant temp were getting that high, you should definitely hear it roaring a bit when the engine is revved. While you're doing maintenance, wash out the A/C condenser, and wash between the condenser and the radiator. You'd be surprised the crap that builds up in there.