91 ford explorer 4X4 auto V6 4.0. When the engine is cold it runs fine accept for a whining noise under the hood. But when it warms up and I come to a stop for more than a few seconds it starts to idle rough and dies. If I hold the gas pedal down just enough to rais the idle it doesnt die but it cant be good for the car. What is causing the idle problem? The idle is set properly so what else could it be?