Lately when I start my truck up if its cold, it sounds like a fog horn coming from my throttle body (acufab S/B) It did this once or twice before, but now its getting bad. Any idea's???

 

opccasionally after a startup and I rev the engine slowly at low rpms the intake sounds like a heavy duty vacuum cleaning, it suckes like 20392048248204802 tons of air in but its not lol

 

Whip, we saw that alot down here in Texas last winter also. I found that the end of my air filter was vibrating like a drum. Think the cold made it stiff and caused the horn sound till it warmed up.

 

The sound called a (Hoot) by Ford, is caused by the IAC valve on the right side of the upper air plenum, if your truck is still under warranty they should replace it free. If not , you can take it off (two 8mm Bolts) and clean inside the ports with a good carb cleaner and reinstall