2002 Taurus problem.
My wife's 2002 Taurus has been difficult to start on cold mornings lately, and with 72,000 miles on it I decided to change out the spark plugs.
The factory gap setting is .044, and all the gaps had opened up to about .065.
I changed them out and took the car out for a drive, and under heavy acceleration it would begin stumbling and had no power. The check engine light came on, so I took it to Advance Auto Parts where I bought the plugs. They read the code, and it said "cylinder 1 misfire". I figured the plug must be bad, so I bought another plug and changed it out, but it didn't fix the problem. I then thought that perhaps the connector in the plug wire had separated when I replaced the plug, so I bought a set of wires and replaced the wire for #1 cylinder. That seemed to fix the problem initially, but on the way home it started acting up again.
The only thing left, as far as I can tell, is the coil itself. Is it possible that the new plugs caused the coil to go bad? I swapped out the plugs one at a time, so I know the wires aren't crossed.