Overheating problem

Hello and thanks for reading another 2.7 v6 overheating problem.

I own a 1998 Chrysler Concorde with a 2.7 v6.
I recently had to rush to an important event I put the pedal down twice and most likely made this engine do things it hasn't done in years.

I noticed soon after a swift rise in the temprature on the gauge as it soon overheated. My first impression, it must be the thermostat, so I changed it with a clean install. I also changed the coolant bleeder assembly. I also bypassed the heater core and applied the proper coolant and bleeded the air from the motor properly.
I have also flushed the radiator and checked the oil several times for a creamy mix of water and oil, luckily no water in crank case. Yes both fans work and I noticed two speeds in the fans, also the engine rides around from dead cold for a good 4 or 5min before the gauge goes up, it rides half way for a couple more minutes then it goes straight up to the overheating level!
What I really hope it is not, is the head gasket/s or the water pump due to the difficulty of removing the pump and or heads.
Also there is no oil in the radiator.

Can someone tell me if I am missing something other's may have failed to mentioned? Also it should be noted, that I too had no heat come from the heater but a couple times during testing on the road when I nailed the throttle again and surprisingly the heater worked and man was it hot!
It never worked again after that. I should also mention that the AC was on and working the day I got on it and this problem started but will not blow cold now.

Would you also please explain the proper precedure for flushing the radiator, I may do this one more time.

Thanks for your website and help to us all!

BODA