Hey guys,
Whenever I come to a stop or let off the gas the RPM's go down to about 600for about 5-10 seconds then drops to 400 and jumps back up and back down until I give it some gas and sounds like it wants to stall. Usually it idles just under 1000. I had new spark plugs, plug wires, and a new fuel filter put in at a local ford dealership over a week ago. What could be causing this? It just started doing it this morning. I doubt it was cause of the cold weather but it was 9 degrees this morning. I also had the Idler pully replaced a couple years ago. Any ideas???

 

Sounds like the IAC and/or the MAF is dirty - could also be a dirty throttle body.