96 jeep cherokee straight 6 4L

i just replaced both top and bottom radiator hoses, no leaks there on good, i filled up my overflow with water and under the radiator cap. yet the jeep still says its like 300 degrees? i need to replace my o2 sensor because its bad so i got it unplugged but it looks like the o2 sensor is connected to the cable end of the thermostat sensor on my thermostat housing. could it just be because my o2 is unplugged? the engine was hot enough to start sizzling water i put a drop on it to see how hott it really was. also all fuses are good so what would cause this overheating?

also i have replaced the heater control valve already too, no leaks anywhere, and the actual thermostat was good a couple weeks ago..so thats the last time i checked it

 

Did you run it for a while with the cap off to let the air burp out?
Turn the heater on, take the cap off and run the motor until you see water moving swiftly in the radiator. Turn it off, put the cap on. Check radiator level when it cools off and add as necessary.

 

You refilled it with water? Well, you need a 50/50 coolant/water mix... That's the first place to start...

 

just the dash gauge saying it? constantly running at 300 would show other signs
could be a bad sensor, gauge or air trapped by the sensor

not exactly a scientific way to determine overheating
is it boiling over?
any coolant in the oil?