S10 overheating
 

So my 1989 S10 is overheating. It was initially due to a failing and leaking water pump. I have since replaced the water pump with a new one, as well as the radiator cap, thermostat, and fan belt. The fan clutch seems to check out as well. I haven’t noticed any leaks or white smoke from the exhaust.
When idling my temperature gauge keeps rising to around 230 degrees, but not spiking, and then my thermostat eventually opens and it comes back down to normal 195-200. I can’t seem to get the temperature to stabilize. I have replaced the thermostat with another new one. I checked the thermostat on the stove in boiling water with heat gun and it was opening at 195.
I also ran the engine without the thermostat and everything seemed to be circulating and stayed around 100 degrees.
Any advice??! Thanks