Have you checked to see if it's running too lean?
How do I check that?
What is the mixture ratio of the coolant, and did you use tap water or distilled?
Are you basing your temp readings on the oem gauge or are you using an after market gauge, if after market what is the temp?
Have you considered using a small pusher e-fan on the A/C condenser?
50/50 coolant with tap water, oem temp guage(runs at the line before red), no room for a pusher fan. When the temp gets that high(the line before the red) the temp sensor for the a/c shuts the a/c down until the temp comes down a few degrees.