[NoNeck]

Sounds like a "Dead" cell in the battery. Since all lead/acid batteries are constructed using a series of lead cells sometimes a cell will become internally grounded or lose connectivity somehow. When you start the engine, a random battery cell produces reserved current to the starter solenoid. Kind of like Russian Roulette. Your truck will start until the bad (or Dead) cell is called on.

My advice, get the battery checked out at your auto parts store. If the battery is old, if your truck has rarely been started over the winter or if the battery has been stored on concrete, chances are this is your problem.

POP