How long has this been going on?

Is the A/C condenser, in front of the radiator, clear? A collection of bugs can block air flow, and more speed won't help.

Is there any difference above 40 mph with and without A/C? The new radiator may be partially plugged, or the new pump may not be flowing enough coolant.

Did this develop right after the radiator, pump and thermostat were replaced? Some thermostats have been 'bad' right out of the box, and on top of that, they can be installed upside-down with bad results...

Is the upper radiator hose stiff and under pressure even after the engine has cooled off? A blown head gasket can result in hotter temps.

Best Regards,
Jim