fat kat

I am experiencing the car runs hot (100c) in stop and go traffic, but is fine on open road (80c) I've changed the radiator, fan clutch, about 5 t-stats, hoses. It all started as the duo valve exploded during a NYS inspection. Does anyone have any helpful tips? Just spent $2,000 on wiring harness and numerous sensors that shorted from deteriation of insulation due to excessive heat build up in engine compartment.