Ford Repair: Air idle sensor/Mass Air Filter/Fuel pump, poor quality air, mass air flow sensor

Question
I have a 99 Explorer XLT 4wd and was told there's a "noise" in the engine. It doesn't qualify for the recall on anything other than a bolt for the reclining seat.

A mechanic (whom I do not know well) has told me, after having the vehicle over 2 weeks, that the vehicle needs an air idle control sensor and mass air filter replaced (coupled with a Throttle Body Cleaning = around $500). He also "found" that the Fuel Pump Regulator valve is going bad but does not need to be replaced immediately, just soon (=around $500).
Do these sound reasonably priced and like something that should have to be replaced? The problems only occur when the engine  is cold.  I had the transmission replaced 1 yr ago so I'm pretty frustrated right now.

Thanks.

Answer
You described the problem as a "noise", but you didn't state what type of noise.  The only noise that I have ever heard from an Idle Air Control (IAC) is a "Hooting/Howling" noise (a loud humming).  I have never heard a Mass Air Flow Sensor make any type of noise.  I have seen vehicles with the wrong air filter installed, or poor-quality air filter that came apart and damaged the MAF Sensor.  The price that you were quoted sounds reasonable, if all of the parts are necessary.
I would expect the prices to be:
IAC - $95.
MAF Sensor - $175.
Air Filter - $20.
Labor - $225.
T/B Cleaning - $50. (Sometimes free w/other service)

I can't remember ever changing a "Fuel Pump Regulator Valve" on this type of vehicle, but that doesn't necessarily mean that yours isn't going bad.  I might get a second opinion.

I hope this helps,
Dave