I'm thinking you need to put some restrictors in the 2 top hoses, such as you would if you had a thermastat or restrictors in the return to the radiator. i run a washer and restrict the flow to 1/2" volume return with a thermastat housing. In other words the water is not staying in the radiator long enough to cool down, it will never run cool. You need to slow down the flow so the radiator and fans can do their job.
JMO
Zip.