Hunting Idle

[DandysRanger]

Hey Gang,
The Ranger is running pretty good at the moment but it has begun idling a little rough. It will be fine and all of a sudden the idle will drop and chug for 10 sec or so and then it will recover and be fine. It will cycle on and off like that for as long as I am at a stop light. If I gas it a little it will straighten right out and be fine. I replaced the IAC valve a few months ago but it did not really help. I have not pulled codes yet but I suppose I probably should. It has had a recent tune-up with cap and rotor and plug wires. I also replaced the coil.
I was hoping someone else had run into this...
TIA,
Jim

 

[RonD]

If possible the next time it does it, unplug the IAC valve to see if the IAC Valve is causing it or a vacuum leak

 

[bfrost]

check the egr. maybe clean it out. sounds like something mechanical that's sticking or a vacuum issue. mine is kind of doing the same thing but haven't trouble shot it yet, its a small problem and I had bigger issues to deal with.