Hello,

2005 Ford Taurus
Car overheats when engine cold and I step on the gas pedal for a semi-steep hill.
Engine Temp Gauge goes ALL the way up.

Then, I turn the inside heater on to release some heat into cabin.

Car stops heating and goes to normal.
After that, it does NOT heat up again. It drives normally.

I thought it might be a clogged thermostat, so I replaced it but NO change.
It still heats up when engine cold.

I noticed that iit's only when I have left the car to sit for a long time (6+ hours) and I drive it on a cold engine.
When I step on that gas pedal ..... It feels like the engine looses power and the car heats up unless I take the foot off that pedal.When engine cold, it drives normally on streets and freeways so long I don't press the gas pedal too long.
Once the engine is hot, the car runs fine: it never heats up again.

Any thoughts?
Thanks!

 

Use a scan tool and see exactly the engine temperature the computer is seeing.Could be temperature sensor feeding the computer some corrupted information. If the engine is actually running that hot, it sounds like there is air in the system and the cooling system needs to be bled of the air.If an air pocket situates itself behind the thermostat on a cold engine, it will not open.