my 4.6l 3v 6spd has a tendancy to stumble and chatter in town around 30-40 kph. dealer told me it needs a spark plug change.pressing the tow/haul button temporarily helps but it can do it in tow-mode also.truck is not a work truck but driven like a car-equally town/country.does 2010 4.6 3v have the same sparkplug removal problems as earlier models?