95 Legacy overheating

[steamboat26]

Hi, I'm new here and I have a 95 Legacy LS with 162,XXX miles on it and have been having a problem with it overheating. After 5 or ten minutes of driving, the thermostat is midway to H, and it has gotten past 3/4 to H, after that I crank up the heat to cool it off.
I know this could be a number of issues. I just had the thermostat replaced, it may have been installed improperly, or it might be a defective thermostat.
I have checked the coolant and oil, they both seem to be at good levels. There is no milky coloration to the oil, so I imagine that knocks out the possibility of head gaskets. Should i look into a radiator flush/replacement, new thermostat, coolant flush, something else entirely?

Thanks for the input.

[Huffer]

You probably have an airbubble in the coolant system.

Take the coolant reservoir cap off, start the car and let it come to operating temp, and gently squeeze the hoses to help "burp" the system. As the coolant level begins to drop, just top it up slowly.

This might take a few attempts.