In most places, gasoline properties are varied throughout the year. to reduce emissions while improving driveability. The Reid Vapor Pressure (RVP) is a measure of this volatility. Winter fuel is more volatile than summer fuel. High volatility fuel helps the car start quickly in cold weather but evaporates more quickly in summer putting hydrocarbons into the air. Low volatility fuel works great in summer in warm climates but makes starting in cold climates difficult.
So how is this fixed? The RVP is varied several times per years in different regions. Here is a chart describing the requirements.
Car with fuel injection make an estimate and correct for this based upon several factors: the current temperature, the temperature when you last turned your car off, the time since your last fill up, the average fuel correction needed to achieve stoichiometry over the last 50–300 miles, and other factors.
Most older carburetor cars do not have this capability. They do not correct for a fill-up of drastically different RVP.
You might be using older gasoline or gasoline with a less than ideal RVP.