1999 Chevrolet Lumina Chevy Lumina coolong problems

I have 1999 lumina it has a brand new radiator brand new water pump brand new hoses, and it still overheats. I looked at it today thermostat was locked up I take out the thermostat it was driving great to get on the freeway turn on my air conditioner it started to overheat pulled over let it cool down I added some more fluid in it I noticed before that there was fluid all over the area where the radiator cap is doesn't look like much not the whole amount that's in the radiator but it came out don't know where. I thought it was the AC so I turned off the AC drove 822 miles on the freeway was doing great stage right above the cold when I got off the freeway and start stop and go it climbed super fast and the same thing happened. No milky residue in the oil or white exhaust so I don't think I have a head gasket blown there's still water in the reservoir that does not leave any ideas. Please help me I'm lost here I have no more ideas thank you so much this Chevy owner.