I was driving on the highway one day and the gas was about in between the middle mark and the E, but a bit closer to the E. Then my truck just started to lose speed even though I gave it more gas. It just didn't want to gain anymore speed. It soon just died and I rolled to a stop on the side od the highway. I tried starting it back up and it was trying to crank, then I tried again and it just wouldn't crank anymore. I haven't drove the truck since then, like a few months ago, and now I have to use jumper cables to give it power. When I try to start it, it will not even try to crank. All the fuses are good. Right now Im guessing it is the starter but I want to know what other people think before I waste time and money on the starter because my dad is a good mechanic and he says it is not the starter, he says it is something inside the engine that is messed up. What would cause my truck to just stop gaining speed out of no where on the highway?