Long cranks when engine is warm.

Had that problem and it ended up being a bad engine to chassis ground. There are three ground wires, two from the battery negative that go to the engine block and inner fender and one that connects the engine to the body back by the firewall. Do not start tracing electrical problems until you verify that all grounds are not leaking voltage while the truck is running and high beams on. Search 'how to do a voltage drop test' on your favorite search engine. Good luck!