My F-150 will not restart after it has been driven and warmed up. It drives and runs fine when started cold, but won't restart after it has been shut off. I have to wait 20-40 mins to let it cool off and restart it. I have been told to replace the starter, before i do i wanted to have some others imput on the situation. Any help will be much appreciated!

 

Also when i was out earlier i ran into a buddy and turned the truck off, then it would not start, tried to hook up the jumper cables and try it but had no luck.