99' Avalon changed everything still overheats

Hello- I just bought and replaced a brand new radiator, new thermastat, water pump, both hoses upper and lower, and both knock sensors.

I can only drive like 20 miles (must be highway or overheats quicker) before it starts bubbling in the reservoir. So I have to let it cool down, slowly take off the radiator cap, dump the reservoir into the radiator, and then add more fluid. Over and over and over.

If anyone can offer some insight as to what I'm missing or something to check I'd appreciate it.

Did you bleed the system? If not, do that. There may be some air in your cooling system somewhere and that can cause overheating.

Is there a milky color to the radiator fluid? Sounds like a leaking head gasket.

Make sure you installed the thermostat with the jiggle valve on the top. It permits bleeding.