This car drives well although the idle seems a little low (slightly rough idle when warm). Yesterday after about 30 minutes of heavy traffic it went into overheat and blew a heater hose. The drivers manual says its normal to get near the red zone when experiencing long idle periods but I was wandering if anyone new of a way to keep this M44 cool? Water pump is less than two years old. Coolant is green and fresh; water pump is upgraded with plastic housing but metal impeller. Serpentine belt is new and tight. Any suggestions would be greatly appreciated.