i have a 98 ford f 150 and when you try and start it,it starts but then it dies.sounds like it is starving for fuel.the only way it will stay running is at high rpms.as soon as you take your foot off the petal it dies. PLEASE SOMEONE HELP!

Idle Speed Control Motor??

Have you looked at the obvious things like a fuel filter on down to the fuel pump? If that filter is really bad, I would probably look at the injectors as well.