My 2000 Explorer was left idle for about 3 days. When I went to start it, it started but as soon as I released the gas pedal it would shut down. It did this several times, and then it stopped. The next day my wife had a similar problem. I them tried and it started OK. It has been OK since then, about a week now. What could have caused this? I thought it might have be an evaporated gas bubble or bubbles in the line–I live in the tropics.
Sounds like a flaky IAC/idle air control valve.
Heres a link that tells you all about it.
The IAC is around 60 bucks at Napa & a couple minutes of your time to replace it.
http://www.ford-trucks.com/forums/166103-iac-repair-help.html