Re check hoses is a good start, also check for a thermostat, running in garage is one thing on the road another. If missing or stuck open will not give coolant time to cool between cycles. Check fan clutch for operation at operating tempature should have a severe noise increase ans air volume increase 15-20x when reved over 1500 rpm. Had a F*&^ van drive me nuts one time and would cool ok in shop but overheat on road... bad radaitor, partially plugged at bottom, take a ir theromoter & look for hot/cool spots in core, just because its new dosen't mean its good. Freash rebuild?? check for exaust gas in radiator, poss leaking head gasket will do it too. Blue water chemical turns yellow take it apart it's internal....
Good luck
Brad
