2002 Windstar misfire at idle

My 2002 Windstar misfires slightly at idle when warm. It does not seem to do this when cold and it's only enough to let you know it's misfiring. Other than the miss, the idle is pretty smooth. The codes I've gotten are for a misfire on cylinder 2 and cylinder 5. Sometimes I get both of these, sometimes I only get one or the other. I've changed the coil pack even though these two cylinders aren't on the same coil. The spark plugs have a whitish accumulation on them in these two cylinders. It also doesn't always do this, sometimes it idles perfectly fine. Power seems to be normal under a significant amount of throttle but the misfire can sometimes be felt when cruising with light throttle. I've replaced the plugs, wires, coil pack and done the isolator bolt fix. The compression check I did showed all cylinders within 20 pounds of each other. I also replace the valve stem seals to help reduce oil consumption (about 1 qt every 800 miles now) and didn't find any broken valve springs. Any help would be appreciated. Thanks.

Did you replace the coil pack with a new one or used? These coil packs don't last forever ... or even a good long time. I have just bought my third (or perhaps fourth) coil pack for my '99 ... 370k miles. Cables can also give problems. After that its cam and crank pos sensors .... then ??

The next time you get a code, swap the cables at the coil pack ... cyl 5 and cyl 1,, etc. See if the misfire relocates.

I've replaced the coil pack with a new one a few times and the wires with no improvement.

Have you tried swapping the cables at the coil?

I have also replaced my coil pack a few times ( My 2001 is over 275 K miles) for a severe misfire. However, from time to time this engine who has never been rebuilt yet ( like the 120unce' one :):):) ) has some light misfire and I have used an old timing light hang on each cyclinder to locate the misfire. The timing light was showing an intermitent miss on one cylinder (fortunatly at the front) I have removed the specific spark plug to see that it was almost totally flooded with carbon and deposit. Because of the milage and the age of the engine, I have realized that the valve seals are totally dried or broken which made some oil so enter in this specific cylinder causing the misfire. Take a look on the spark plugs that seem to misfire and clean or replace them if necessary.

Yeah, I "rebuilt/refreshed" my engine at 215k miles. Could have gone further without any work, but I wasn't sure 'til I got inside. 200k - 300k miles is all I think we can expect out of todays engines before the seals and gaskets start to fail ... even if metal wear isn't severe enough to require a rebuild.

Did you replace the coil pack with a new one or used? These coil packs don't last forever ... or even a good long time. I have just bought my third (or perhaps fourth) coil pack for my '99 ... 370k miles. Cables can also give problems. After that its cam and crank pos sensors .... then ??

Ford used a different coil pack starting in '01, waterproofing on the connectors was improved and the pack does not sit right underneath the leak-prone windshield gutter collector as it does on ours. Actually I suspect that this collector is the main culprit to blame for coil pack issues with the '99/'00 models. Unless the seals are perfect it drips water directly on top of the pack. In theory the new pack should last longer.