Do not forget the
oil. Do you have an
oil cooler and is it controled by a T-stat? Engine
oil runs about 40 to 60 degrees hotter than coolant temp so if at 220* coolant and oil can be 40 plus degrees hotter then the recomended max of 260 * may be an issue. You want oil to reach 210 so contaminates are vaporized.
I bet you have a 200* coolant T-stat I would drop to a 180* unit and folllow the other good ideas already mentioned here on this thread.