My car has a Teggy engine, in my case it was a faulty Fast Idle Thermo Valve, which is on the bottom of the throttle body. I bought a plate and blocked it off.
Apparently as they age, the expanding wax starts to not expand anymore and doesn't block off the extra air passage that raises idle when cold. My car starts fine cold even with it blocked off but it doesn't get sub-zero here.
CUSTOM BILLET WORKS