I have a 2007 F150 4x4 with 4.6L V8 and 5-spd manual.
Less than 10K miles.

Cold starting is fine, but it has a hot start problem. When
hot, the starter spins the engine OK, but it won't start.

Ford ran a diagnostic scan and couldn't find anything
wrong. Naturally, the problem won't occur when I take
it to the dealer.

Anyone had any experience like this? Solutions?

 

normal, mine does it, leave the key in the run position for a sec before starting

 

Did they check your fuel pressure? If not you want to read the gauge and see if any drops off after you turn the car off.

I would bring it back to the dealer. I wouldn’t say this is normal. If you need to keep the key in the run position so the fuel pump gets some fuel to the rail its not functioning properly. I recommend testing the pressure drop off to see if there is really a problem. It might be loosing some pressure and vaporizing some fuel causing your hard hot starting.