Since you have done so much, there is little left to consider. If the vehicle is still overheating at highway speeds, as well as slower speeds, I question the following.
1) Possible bad thermostat (even though it is new) or was installed upside down.
2) Possible lower radiator hose collapses.
3) Possible head gasket issue.
4) Timing issue.
5) Still a partially plugged radiator.
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Wednesday, November 22nd, 2017 AT 4:24 PM