replaced spark plugs but why do I still have hesitation?

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! If you’re still feeling hesitation after replacing the spark plugs in your 2014 Ford Explorer, it could be a few things. Since the problem happens uphill or when accelerating, you might be dealing with a failing coil pack, clogged fuel injector, or even a dirty mass airflow sensor. The cold engine part makes me think it could be a possible head gasket issue. Checking the misfiring cylinder for coolant in the morning might help determine that. Replacing the plugs was a good first step, but one of these other areas might need attention to fully solve the hesitation. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554!