Cylinder #6 misfire

I've just been told after two trips to the mechanic cyl#6 is misfiring. It only gives a soft code (check engine light flashes for 30 - 40 seconds then goes out) so it was hard to detect. Problem only occurs when either sitting at idle with electronic climate control ON especially when the A/C compressor kicks on or going up a hill, accelerating on to the expressway for example. It's the DOHC Duratech engine in a 2003 LS Premium.
He has suggested starting with changing the spark plugs first. Next the wires and then finally the coil pack. How does a coil pack differ from the old style coil and would it be possible for only one cylinder to be affected by a defective pack?
Finally, any other ideas?
Thanks for your time.

Yes! Roll the coil pack.
If not the Spark plug, wire, or coil, do the injector next.

Thanks for the reply. Tried plugs today. No change so wires tomorrow.

I have the same car. Mine will misfire if the plug wires get wet. The last time I power washed the engine some water got down in the plug cavity. Dried things out and everything is fine. I would suspect the wires. The coil pack is probably fine, never heard of one going bad on one cylinder only. I suppose it is possible, but unlikely.

Since you have the exact same car. I was just wondering if you have had any problems with that electronic climate control unit not working or the dash cluster lights going out ?

Good luck