I have these exact issues with my 2006 LC 100.
If temps are over 90, and I am driving for extended periods of time, always around Denver or higher elevation, sometimes as much as 10,000 ft......
My truck will start stumbling and die sometimes at a light, or won't re-start if I shut it off when hot.... the starter will turn and it will stumble around and not start....
My first fix is to stop in a parking lot somewhere if I have to cut the engine off, and then open the gas cap and let if vent for 5 or 6 minutes at a time... this has worked the last 3 times I have had the issue....
Then, I figured something else out.....
The fuel I was running was typically mid-grade for elevation here in Denver, which is 87 octane, and I have even had the issue when running the highest octane, 91; the issue has happened more when running grocery store gas (loaf and jug or Safeway gas) than higher quality brands.
I have an ethanol-free fuel pump only 1/2 mile from my house, and even though it costs $1.00 more a gallon than regular Premium, I have been running it when the temps average above 85 and I will be driving in high elevations or far off-road for work. Ever since I switched to this ethanol-free fuel, I have not smelled any vapor release ever again, and I have never been stranded or had to wait on vapors to release or had a no-start situation since.
My take is that the 10% ethanol fuel is having issues with vapor-locking because the evaporative system is not set up to deal with fuels like this, at this temperature, and at this elevation, along with a lack of heat shielding and insulation of the fuel lines up and down the entire vehicle.