When car has been sitting for a day or so starts up fine. Start to drive lack of power (feels like a few cylinders) almost feels like it's going to stall then it kicks in and runs normally. Only happens when car is cold. Problem just started as the weather has become colder. Any advice and solutions greatly appreciated. Have not taken to a Hyundai dealer. 2010 Hyundai Sonata Gl, 4 cylinder automatic with 44,000 kms. Bought new, never have had any other problems. Regular maintenance oil, filters etc. maintained.