My 1990 Cadillac fleetwood starts good in warm weather not in cold weather

Hello, This is likely an issue with the idle air control valve. When the idle air control valve has issues, it does not allow enough air into the engine at idle, so starting and idling are troublesome. Cold weather can exacerbate the issue. Of course, diagnosis is needed, and the EGR valve for the Northstar is also known to cause this issue.