Most times when I start the truck, as I shift out of park into drive, the truck lurches forward. Luckily there is no one/thing close by.

I was driving one day and came to a stop at red light, 20-30 seconds later I swear I was rear ended. Got out and no one was around, drove a few more miles stopped at stop sign and bam, happened again, the whole truck shakes and feels like you've been rear ended doing 40. Taken to dealership 4-5 times with same answer as nothing is found. It doesn't happen every time I drive it but once it starts it does it every time I stop until its parked again.