1995 Ford F-150 I began to notice my engine would hickup when towing my boat up a hill. The problem has grown progressively worser, and now just a slight incline can cause this problem. The other day it did it without towing anything. It's kind of like a quick 'thud' or hesitation from the engine. I don't have a tach so I have no idea what my rpm's are looking like while it's going on. It feels like my engine is still in gear though. Any idea what could be causing this?