I have a 2008 Ford F-150 lariat with the 5.4. I've had a little jerk going up hills for years and never paid it any attention. Recently every time I pull a trailer it will jerk even worse. When I slow down to a roll or completely stop it starts making a knocking noise. It will do it for a couple of seconds then stops. It causes my check engine light to come on. Every time I plug it up at o reillys it reads cam position sensor. Ive changed both cam positions sensors, fuel filter and all plugs. Nothing has helped. Does anyone know what it may be?