First, when the truck is at a stop (red/stop sign), acceleration fails, resulting in a sudden, hard jolt into gear or a complete loss of power. Near rear end collision occurrence avoided several times. Second, while driving 0-30MPH there is a constant hard swift into gear causing a forward/backward jolt of all passengers. Last, and most significant, is the sudden loss of power experienced with highway driving. While driving 75-80MPH, sudden deceleration occurs. The gears shift spontaneously from 8/9 down to 1. Speeds are not capable of being manually controlled, by the driver, at that time. What happens next, is either a sudden jolt into gear following deceleration or complete Loss of power. Collision was avoided by pulling off to the side of the road. This sudden deceleration occurs also when attempting to merge into highway traffic. Here again, a rear end collision was narrowly avoided. The truck was serviced to evaluate the cause of this issue, by independent service station technician (vehicle no longer under warrant). They stated that the transmission was the problem and, after consulting with Ford, a computer upgrade was performed. This unfortunately had no impact on the above problem, despite following the recommended ‘break in’ time. Currently the truck is not operable as the transmission is too unpredictable and erratic, rendering it unsafe to drive. This truck currently has only 46,000miles. Ford customer service was notified of this problem who in turn suggested we contact NHSA regarding this complaint. Incidentally, a family member with the same year, make and model truck had the transmission replaced, just this month, because of similar power train operational issues. I encourage the NHSA to evaluate this matter, as POWER TRAIN FAILURE is a known issue with this particular vehicle. Most importantly, this is a concern which poses a significant impact on overall public safety.