95 at speed shouldn't be a problem for rhe the cooling system. Does the car still have the plastic undertray under the rad and engine? Need that for the air to actually go through the rad.

Bucking sounds more like fuel pump going out. What was the fuel level in the tank when this happened and does it happen even with a full tank?

 

Stock plastic under tray still in use. Problem is more pronounced when quarter of a tank or less. Now it’s starting to happen even at 3 quarters of a tank. The fuel pump (Mazda OE) is 9 yrs old.