I also live near philly and have the same recurring problem. Do I see that you also drive a Jetta. Mine has had the check engine (emissions) light come on frequently. Each time the code says mass air flow sensor error. The car has been checked for vacuum and coolant leaks and the sensor has been replaced numerous times but the problem keeps coming back. I’ve noticed that the last 2 times it was when the weather suddenly got cold again and the gas tank was less than 1/2 full. Did the dry gas help you out?