Have a 06 4.4 since new about 7,000 on it now.Since i have had it i feel it has a miss,hesistation,tranny problem when i start from a dead stop. It never feels smooth always jerky.Anyone who drives it also mentions this without me asking them.Dealer tells me about VANOS but i do not believe him.Also truck is slow to downshift to pass unless you hit pedal all the way and rough downshift when coming to a stop. Any ideas ????? thanks