Urban, it's not an issue of a sensor reading causing the moaning noise. It is just a well known fact that the IAC on these things make a moaning/howling noise, especially noticable at idle in warm/muggy weather. If you remove the airbox cover, the noise becomes foghorn loud. Known fix for this phenomenon is to clean or replace the IAC. Been there, done that.
Chris - not sure if cleaning will fix your MPG issues. Usually, bad IAC will result in moaning and either inability for engine to idle, or too high an idle. If your truck is idling fine, then other maintenance items - plugs/wires/air filter/fuel filter/thermostat etc. will come into play. Where is your temp gauge running? Is it consistantly near the middle of the guage? I'm on my 2nd thermostat. If engine is running cold, then the temp sensor will never tell the computer the engine is warm, engine will run rich -open loop mode- continuously. Also, our NE cold weather ethenol enriched gas will take a mile or two from the MPG.
