cooling issues

Calculate the expected temperature drop (inlet temp - ambient temp) * radiator efficiency = xx degrees

Lets say that inlet temp is 220 and the ambient temp is 90 and the rad efficiency is 50 percent, that would be 65 degree drop at best from inlet temp to outlet temp.
Think outside the box, put a c-clamp on the upper hose....that will restrict the flow :)

Maybe the old radiator was "restricting" the flow enough for it to cool down by the time it made it to the outlet, or maybe the fan clutch is bad??