My jeep starts and seems like it's going to quit. This only does it if it's been parked for over 18 hours. Recently it has been making like a groaning noise when I start it and it stalls. After that it starts up fine. The noise is not a screeching sound. It only does it on the first start and when it's cold outside. No one can tell me what's wrong. I had the battery, spark plugs and water pump changed. The fuel injectors have also been cleaned. The alternator and starter have been checked and they are fine. Could it be a bad wire or something that is plugged. Thanks.