I don't think it's the gas but the fact that the car is at operating temperature or running a bit hot.
hot starts can be an indication of:
- bad ignition coils or plugs
- failing catalytic converter
- bad starter
- low compression.
lets start with getting a few more details on your car. What year? how many miles? original owner?
last time you checked / replaced coils?
how old are the plugs?
any major modifications?