[wiswind]

If the problem is gone....don't argue with success......
One thing that comes to mind with the 1999 and newer Windstar with the "Isolator bolt" issue is the FORD TSB that gives a reflash of the PCM that slightly retards the timing.....
The issue is that if the extra oil vapor enters the engine long enough.....carbon builds up inside the cylinders, which increases the compression.
My solution, OVER delay of timing, would be to use a higher octane gasoline.....try 89.....and if that is not enough...try Premium.....92 or 93 octane (US values here).

The above thread.....spark plugs.....brings up a point that I have mentioned many times.
Address ANY routine maintenance items BEFORE looking to the exotic or expensive solutions.
Many people drive a vehicle until something goes wrong......there are things that are listed in the owner's manual that need to be addressed at specific times/mileage.......look to those FIRST.