I had an intermittent starting problem on my 05 stang. It would act just like it was vapor locked and would not stay running. This occured after running around a bit, then sitting, and then I'd jump back in to run somewhere else. Wouldn't start..... when it did, it would barely run and if you tried to add any throttle it would die.
Probem turned out to be a bad inertia switch. Couldn't believe it myself, but it fixed it!