[rick3000]

I installed a new OEM Pierberg water pump.

The only other thing I can think of is that there is an issue with the actual radiators, but I have never had a WP impeller fail, so I don't think there is any blockage. The car warms up normally to 180 and stays there for several minutes, but then it just seems like the cooling system cannot keep up with the outside temperature and the temps start rising unless I'm going 50mph+ without stopping.

Everything is perfect in cold weather, the coolant temp sits a tick below 180 with the 160F thermostat.