Today on my way home my truck started making a wierd noise. As I got off of the freeway I came to a stop light and when I started to go again it sounded like the truck was reving up but I had no power. I let it cool off and drove it again and now it seems to be fine. I have had this happen before and I have no idea what the problem is. It seems to happen at the end of long drives. The last time it happened I was driving for about 2 hours over a mountain range. Please help.