Ford: Ford Explorer, faulty valve, throttle valve

Question
I had the IAC valve replaced on my 98 ford explorer about 3 months ago.  The RPM's would shoot up to about 3000 rpm when the engine was warm and in park or neutral.  It started to do the same thing again, but not to 3000 rpm but around 2000-2300 rpm.  It doesn't do it all the time. Ford said it isn't a faulty valve but the throttle body needs replaced.  A local shop said they have never needed to replace a throttle body on an explorer, though it could be the problem.  Any thoughts?
Thank You.

Answer
Ron, I seriously doubt it.  The problem I have found with those intakes is that they take in oil like a kid with candy.  You have to keep them extremely clean.  Start spraying air intake cleaner trough the throttle valve body.  Replace the PCV valve immediately.  If you really want to make it run better, take off the intake and have it boiled.  You can have this done at any machine shop fairly cheap, around 30 dollars.  (for the boil, you will have to take it off yourself to get that price)  I don't usually disagree with what a shop says, but I can't see the valve body being bad.  There really isn't much to it.  Do you have a check engine light on?  If you do, have it checked at Autozone, they will do it for free.  Is your truck running less than 190 degrees?  If it is, then you need to have the thermostat replaced.  It will cause the truck to run at a high idle. (basically it is running at full choke because the computer reads the engine as being cold)  Take the truck to someone else other than Ford before you pay that price.  If you can think of anything else that the truck is doing, then write back and let me know.  Good luck,     Jason