96 GMC Jimmy

Truck cranks but won't start first thing in the morning. Thought it needed a tune-up so put new plugs, wires, rotor, distributer cap, coil, battery and finally an alternator. Thought maybe it was fuel so I replaced the fuel filter. The amp guage in my truck reads between 9 and 12 first thing in the morning and that is when it will just crank and not start, as soon as I put my battery charger on it, the amp guage will jump up to between 12 and 14 and then my truck will start. Anybody have any suggestions?