Battling overheating new 360 build
From the picture looks like your shroud is not covering the fan at all not pulling any air through it the radiator I'm not an expert just my thoughts think of the fan and shroud like this it's able to cool at idle because not as much heat generated and with your setup able to pull some air when going down the road the radiator actually becomes close to a solid item air will find the least resistant path and go around the radiator need to force air through it so that's why the proper shroud and fan setup is so important you probably have a combination of things causing this but I would tackle the proper fan and shroud setup first personally I don't like direct drive fans consider putting a clutch on it
