Dies when hot, possibly boiling gas, exhaust flap stuck

Try to keep the valve functional. It really helps the warm up on cold, or high-humidity mornings.

That special penetrating fluid is specifically designed for that valve, and I have seen it at the Ford dealer too, with a Ford logo on it no less. Take your time on it. Sometimes a day or two with multiple applications, just like member nm9 details. It just takes time.