This just started happening when the temp dropped in Oct.--If my car is completely cooled down and it's around 50 degrees or colder, the engine sputters for maybe 5-10 seconds and then fires right up and runs perfect.

If the temp is above 50, it starts right up.

Could this be a coolant temp sensor? How do I check that. There's no SES lights on either.

**I'm pretty sure my car has a bad head gasket because coolant comes out of the radiator cap when I drive it hard. Could this be related to the starting problem? There's no coolant in the oil and I don't see or smell any in the exhaust on startup.

 

Low compression from that head gasket could be a reason for rough running. I'd be willing to bet it is part of the issue here. Things like this stiffel people forever. If I had to guess at it from here I would say do a tune up and it will probably clear up.