Ford diesel help!!!! please?

My dads 2008 ford f-250 diesel (6.4 l powerstroke) seems to have a small problem. When i go to school i leave my truck in the hot sun for about 8 hours and when i get back the first time i turn the key the truck doesnt start and when i let go the motor squeaks. But the second time i turn the key it starts with no problem. It has about 19000+ miles and we give it regular maintenance. I have been a little bit of a lead foot on the truck because it sooo fun to drive. I hit 90, peel out, drop the pedal to the floor from a dead stop. Am i being a deuce bag to the truck? But the real question is whats wrong with the truck.

Tags: Diesel, Ford, help, Please