Q: Engine won't idle when cold - 2001 Chevrolet Silverado

Hi there - given your repairs already, I would suspect a fuel-related issue, specifically the engine coolant temperature sensor (for engine management, not the gauge). If a faulty temperature signal is sent to engine management, the engine may not be getting a rich enough mixture when cold. This kind of failure is masked when the engine warms up - engine will run fine when hot. I would recommend an inspection of engine sensors to resolve the poor cold running you are experiencing by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.