There was an old post about this with the same subject line. I can't
reply directly because it was closed. I am having the exact same
problem though. Usually after at least 12 hours of inactivity, my
Focus ZTS starts, but then dies. The trick I use is to apply the gas
right after starting it, while still in park. This works if I step on
it in time, and rev the engine enough. It runs fine once it gets
going, but I'm worried about this developing into something worse.