The reason that I asked is that there have been a number of reports on the forum regarding poor performance of non-OE water pumps. The problems had to do with the impeller design, which resulted in poor coolant flow.
It's difficult to believe that your problem is being caused by the radiator, considering that the engine was running too cool before. That demonstrated the radiators cooling ability. It doesn't make sense that it would loose that ability all of a sudden.