96 idle problem

1996 W/S 3.8L, 71K miles: CEL on, code reads misfire on #3 cyl.

Have installed new air filter.
Cleaned MAF sensor.
Cleaned IAC.

Have discovered that IMRC remains open at cold start up, however they will have closed by the time the engine reaches normal temp and will open and close as normal there after.

When coming to full stop engine falters/stumbles as if it were "choked down", there is some power loss when accelerating from a stop till RPM's exceed 1000 RPM's.

On full acceleration/kick-down occurs as normal.

Any and all comments/suggestions welcome.....

#3 Cylinder is on the back....driver side of the engine. I am wondering what the spark plugs are like. They are good for 100K miles. But at 9 years..... You can get at the plugs from under the car......if you have ramps to drive the front up onto.
You slide in under the car.....and look up the front face of the fire wall......
I would pull the plug.....and compare with a plug from another cylinder. If you pull the other plug from the front of the engine....you will reduce the chance of switching spark plug wires by having 2 plugs out at the same time.
If you replace them.....I would recommend ONLY Motorcraft brand of DOUBLE platinum plugs.

The other thing that I would consider is the spark plug wires. If you replace them....get a high quality set.

When you remove a spark plug wire from the spark plug.....grab the wire by the boot that goes over the plug.....and twist it.....as in turn the boot on the spark plug....to break the boot free from the spark plug....before pulling by the boot ONLY.

When installing a spark plug wire onto the spark plug.....put some dielectric grease inside the boot to seal out moisture......prevent arking.....and to make the boot easier to remove in the future.

Another ignition possibility is the coil pack. IF it is that.....the most likely cause is a small crack in the epoxy body.....permiting arking.

Fuel system problems would be relative to the fuel injector for the #3 cylinder. This could be a loose connection in the electrical circuit for the injector.
There is power to the injector at all times that the key is in the start or on position. The PCM provides a momentary ground to the other connection in the injector.....which energizes the coil.....and pulls a little plunger.....permiting fuel to flow....and spray into the engine.

It is also possible that the #3 injector needs cleaning. I had to remove my injectors to clean the spray ends.....to solve a misfire on the #2 cylinder. I cleaned all 6 injectors at that time.

EGR ports clogging....NORMALLY causes misfire on cylinder #1 and/or cylinder #4....as those cylinders and ports are the farthest from the EGR valve....and normally the last ports to clog out of the 6.

You might get lucky and be able to help your situation with a high quality fuel system cleaner.....such as Chevron Techron (2 bottles that treat up to 10 gallons).....but a professional cleaning may be needed.

I'd have to guess coil pack. You seem too low milage for EGR ports.