Why it has trouble starting the first time every day, but works fine later, and runs good

Do a leak down pressure test on the fuel pump, the test port is on the top of the engine in the fuel supply rail to the fuel injectors, hook up the fuel press test tool there and then start the engine, check for leaks correct if needed, shut the engine off and watch the pressure gauge it should stay within 5 psi of the highest reading. If the gauge falls off to zero you will need a new fuel pump.

If it only gives trouble after standing unused for several hours, I would suspect the gas lines, possibly. After sitting for several hours, if your gas lines are already gunked up, then it's difficult to get the fuel to the engine after sitting for several hours. Once you use it, and warm it up, then it's not as difficult getting fuel through gunked up lines. Just a possibility.