I need some opinions on an over heating / coolant loss issue that my civic is having.

Got the car a few months ago, went for a long drive on the highway and the car began to over heat.

Replaced the thermostat and the over flow cap to see if that could be a factor.

Replaced the manifold because we noticed a small crack, also replaced o2 sensor.

Flushed coolant system, replaced radiotor, burped the system several times after to release any air.

mechanic suggested it could be the head gasket so picked up a block tester and tested the system, nothing came back to signify it being the head gasket.

so what's happening now is for driving it's fine, but if it sits after driving long it starts over heating and FAST.

both the fans seem to be working, my ac and heat are working fine, replaced the switch for the fans to be safe anyway.

coolant seems to be coming from the over flow cap and thats causing us to lose coolant maybe? I noticed while replacing the rad that the condensor looked pretty beat up and corroded, would this be a factor? I also noticed one hose seems a little worn and has coolant spashed around it and the surrounding area but could also be there from bursting out around the over flow cap...

I'm really at a loss of solutions and was wondering if anyone has any suggestions?

 

Headgasket, very common around 100K.