Mysterious Overheating Issue 206

Hey guys,

I have a 206 with a very strange problem I was not able to fix.

The car overheats on both highway and city driving.

I have replaced the antifreeze, bled the system several times, changed the thermostat, changed the relay and fan speed rezistors, fan works.

The car has fresh new waterpump and belt plus oil.

Eventually the engine overheated so I will swap a new one.

Only thing I noticed that I didn't before is that the car overheats in according to rpms.

Driving with 90 it stays around 80-90 degrees, but as soon as you step on it it goes over 100-110

Please let me know. I know the engine is dead but I want to know how to prevent this if it ever happens in the future