Ford Repair: whining noise, air control valve, excessive load

Question
I have 98 ford explorer It is making a high pitched whining noise every now and then, when in lower rpms or stopped the truck wants to stall, and when driving if the noise starts if you press the gas pedal hard the noise goes away.  Do you have any idea what it could be, and how much to fix

Answer
It sounds like the problem may be in one of you're belt driven components. You can start with you're alternator by having it load tested. As for the stalling, if a bearing in one of the components is going down, it might be putting an excessive load on the engine. Go ahead and clean the idle air control valve with cleaner and a cotton cloth. I have posted instructions in "several" idle related questions. Let me know what you find out so I can advise you from there.