If you have a temp gun check the temperature drop at the radiator necks. 30 degrees normally should work if you have decent water flow. I would bet that fan setup you have is not up to the task. First your not pulling air through much of the core and second those blades are awful tiny. Unless they spin really really fast I can't see them moving much air. Driving down the road will only make a big difference if it's pretty cool outside, during summer natural airflow normally won't be enough to keep a decent motor cool.