2004 Focus problems with starting (old thread was closed)

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.