The air reg you have acts just like a thermosat and it senses engine temp from water passing through it, hence the hoses. The regulator is open when cold and slowly closes as the temp rises, which restricts airflow until it reaches about 145 deg. where it should close fully.
It allows air to bypass the throttle valve, boosting rpms. As the engine temp reaches operating range, the valve closes the bypass and the engine should idle properly.
What happens over time is the air reg valve becomes dirty and sticks or freezes in the cold/open position and will not close.
As a quick fix attempt, you could try boiling it clean or soaking in a solvent parts bath. Worth a try.
I want to die like my Grandfather did, peacefully in his sleep.
Not screaming in terror like the passengers in his car.