Need a Mopar guru: 273 part-throttle ping driving me crazy!

Do this, Start it from stone cold and blast off. Either direction I leave out from my place I have to go down and more importantly up hills. Anyway...
Run the dog crap out of it and I'll betcha you cant make it ping even up hill.
The ping will begin only after it gets too hot.

Yes, correct. After running for about 5 minutes it will ping on a hill/load, i.e., when the engine is getting hot. But, I think the radiator was recored along with the motor "refresh" and everything that goes with the cooling system (new thermostat, new pump, new hoses, etc.).