Same symptom cold or warmed up?
And runs fine other than at idle?
No codes?
With engine warmed unplug the IAC Valve.
Idle should drop to 500rpms or engine may even stall, either is good it means IAC Valve is working.
You could just have dirty injectors, run a can of Seafoam in the gas tank, that will clean them up.
Dirty injectors drip fuel at idle, instead of spraying fuel, this causes a leaner mix which can cause misfires and then the popping noises.
You could also have coil issue causing a misfire(or two) which dumps oxygen and raw fuel into the exhaust pipe which can ignite from a firing cylinders exhaust hitting it causing the popping., the extra oxygen also causes O2 to show Lean and computer adds more fuel making it worse.
Coil Packs can be odd ducks, you can test them with an OHM meter and it will show if a coil in the pack is bad, but..........even if it tests good it can still be bad, so worth while to test but doesn't mean it is good.
Google: testing Ford Coil Packs the easy way
Good video How-to
I would expect a lean code with these:
Dirty MAF sensor cause lean mix, easy to clean this
Vacuum leak, if unplugging IAC valve doesn't drop the idle this could be the problem, not the IAC itself.
4.0l lower intakes are known for having their bolts back out a bit and then you get a vacuum leak, easy to check these for tightness, torque spec is not much, 18 or 20ftlbs I think.
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