Check and make sure the A/C condenser is clear of debris. Also, make sure the space between the A/C condenser and radiator is clear of debris.
When I took out the radiator, I couldn't believe how much gunk/junk was in between.
You should be able to see through the condenser very easily.
If you've changed to R134a and a running the SINGLE aux. fan, change it to dual pusher fans.
I would look at dual 11-inch SPAAL puller fnas (2700 CFM) if they could fit when you remove the viscous fan. You'll need to wire in a Derale relay (everything else out there is junk, IMHO), which is adjustable, and has provisions for turning on the fans when the A/C is turned on as well.
Do a search for SPAAL fan and you'll find my links. BTW- I might have spelled it "SPAl".
PS: you did install a BEHR replacement radiator. . .