intermittend spark

truck stalls no spark waited 2 hours for help trying to start many times been towed 5 times after vehicial has been moved weather it has been towed or rolled down a hill it will start so long as it sits no spark coil tested fine im told if it were a ignition mod or computer it would not start at all but as i said i can start it right now how ever wont get far what oh what could this fustraiting pain in the ASS problom be

Maybe a crankshaft sensor, just a guess. I had a car one time, I would leave work and it was fine. Get home and eat and whatever else, go to leave again and the car wouldn't start. Crankshaft sensor could have a small hair line crack, causing the problems your having. What motor? What year?