Ford Repair: 2001 Ford Escape cylinder 4 misfire, air control valve, spark plug wire

Question
I have a 2001 Escape v-6 approximately 104,000 miles. It started idling rough when first started up then when it warmed up it seemed to idle fine. The engine light came on and I had it tested. It had a cylinder 4 misfire, so i had the spark plugs changed and coil packs checked, they were fine. They reset my engine light. After driving twice about 15 minutes each time the light came back on and idling rough again. I've put the Lucas fuel cleaner in it, that didn't help. Now what should I do? It doesn't lose any power while driving just when setting and idling. Please help with any advice.

Answer
Take a look at the number 4 spark plug wire.Go ahead and put some dielectric grease in between the wire and the spark plug. Change the plug wires if they are older than 2 years to cover all bases.I would recommend cleaning the idle air control valve using a cotton towel and air intake and throttle body cleaner. Especially cleaning and inspecting the butterfly valve of the throttle body.. A sizable amount of carbon moisture can be found at the butterfly valve.As the butterfly stands vertical at an idle and ignition off,the carbon deposits can sometimes "cake up".