no heat / over heating

My 97 Jeep Cherokee is over heating...it will run at 210 for about a mile then the guage shoots to the red zone and the "check guages" light comes on.

I have replaced the thermostat, flushed and replaced the coolant. I think my next step is to replace the sensor.

Where should I go from here?

Thanks

PS I am not getting any heat although the heater is running full blast...Jeep does not overheat as fast when the heater is not on

u have to purg the system. on the back of the block, on top, next to the valve cover, driver side, is the temp sensor. it looks like a small spark plug, with a wire going into it. pull the wire off of it, and un skrew. air will come out then coolent, put it back in, p.s. un skrew the radiator cap, and point the nose of the car down hill, befor u remove the temp sensor. u might have to do this more than once, do every thing run moter to opp temp, then trun off, then do it agin

Are you sure your coolant level is correct? Thermostat in the correctly (front side towards front)?

Did you mean it takes longer to overheat when the heater is off?

was it overheating before you did the work?