After replacing radiator and thermostat, and still having an over heating issue you need to inspect your water pump. You may have weeping from the lower half, indicating the need of replacement, or the front bearings of the water pump could have failed. You also may need to check your coolant temperature sending unit for failure.
Hope this helps!
〉 Answered on Jul 23rd, 2012 by Amanda J. Pierce, MBA "AJ", Certified Mechanic, Project Coordinator; Primavera Scheduler at VIGOR Alaska Industrial Shipyard & BizzM3ch Solutions