1994 Mercedes sl500 150k. 5.0 eng. Car was running hot Never over heating.. I replaced the water pump. Started the car and let it idle and it shut off in 5 min. 80 deg. temp. Let it cool and the same thing happened. Is there a temp. sensor that may have gone bad. Am I looking in the wrong area. The only code that comes up is and old code. Mass air flow sensor.. Need some help ///