Distributor ECM?? Truck runs GREAT. Starts immediately when cold. After driving a bit...esp. on highway for a few hours, when turned off and try to restart, VERY difficult to catch (engine cranks) I had spark plugs, plug wires, ignition cap, rotor, coil replaced. No change, still won't restart as it should. If I leave it off for 15 minutes, it starts fine.

it could be a problem ECM unit or a corrupt CPU program that is upsetting the immobilizer
try using a scan tool to reset the ECM
try using a known good ecm to replace the unit for a test

Alternator is not charging battery starts a car and then alternator runs all power needs...

When it doesn't start, check for spark from the coil.

check the engine coolant temp sensor . the sensor can show a high temperature to the ECM and therefore the computer limits the fuel to the injectors. on cold start up the injectors need more fuel to get everything going until the truck warms up.

The distributor will have white deposits on each metal tap inside cap and the rotor will be worn down. Take a look under the cap try not to disconnect the spark plug wires just unhook the cap and turn it so you can look inside. That's the easy thing to do. If the cap has the deposits you need a knew cap and rotor I would get knew wires and check your spark plugs as well.

when you say it won't start again until the next day? does that mean after turning your truck off it won't start immediately? After a couple of hours of sitting have you tried it again. Are you sure your truck is running fine? is there a sulfur smell or extra warm coming form the floor? It could be your catalytic converter which is clogged, when the truck is cold.. you are getting enough exhaust escaping allowing the truck to run, but it will be very restrictive and I highly doubt that you are getting good acceleration, once this is hot is so restricted that it will not allow the truck to restart.
This can be a serious condition and if parked over dry grass or trash could actually start a fire. Take you vehicle to a respectable exhaust specialist.

Could be a couple of different sensors. MAP, oxygen, crank, or cam sensors to name a few. You will need to have it checked out on a computer to find out what it is doing for sure though.

Not a solution but i am going through the exact same nightmare and same symptoms with my 1991 mazda b2200. I've apwnt over two grand to have my rebuilt TWICE and my alternator replaced and still does the same thing just starts only to die 2 seconds or so later unless i let it warm up to its max but will still die when taking turns and stopping at lights.

Sounds like a fuel issue. If it only does it when it's cold try putting some heet in your tank?

Use a heat gun to dry off all ignition components. If that doesn't do it, start looking into a partially "Hydro Locked" Engine.