When shopping for radiators, pay attention to how they are made. I have Afco brand aluminum that uses epoxy to seal the ends of the tubes to the headers, it is starting to weep at a few of the joints, just enough to smell. There is no fix for it, when it gets to bad it goes in the trash. The next one will be fully welded aluminum.
Heat at idle is an air flow issue, fan and water pump speed matters. I increased my water pump speed by going to a smaller pulley, then replaced the flex fan with a solid 6 blade steel fan. At 650 idle, you can feel the air being pulled into the grill, it's a bit noisy at highway speeds though.
Heres a fun tool to play with,
https://www.blocklayer.com/pulley-belteng
