93 geo storm rough start & stalls at low RPM after cold weather

Hi, I have a 1993 Geo Storm with 56K miles on it. I live in Portland, OR. We recently had a bad storm & my car sat for 4 or 5 days in below freezing weather. Now that the weather has thawed, it is very hard to start, runs very rough & requires flooring the gas to keep it running for a few seconds. It smokes (white-ish looking) during this process. Once the car is running at higher RPMS it smooths out & seems OK. I checked the oil & it doesn’t appear to have any anti-freeze in it so I’m hoping it’s not a cracked head or block. It also stalls & dies sometimes while at a stop light or stop sign. Any ideas on what to check or what the problem might be?