[wiswind]

It was recommended to me by my mechanic.....I had a "misfire" on several cylinders.
I have had this come up several times.....in spite of using a fuel system additive in a "maintenance" dose.....Redline and FP60 are the 2 that I have used in maintenance dose.
Most fuel system cleaners are detergent based......and the 2 that I list above are as well.
I have used others....and like you, found that they did nothing to smooth out my engine.
I once spent months trying to track down a slight miss......and once it got bad enough to light the CEL and have a code......I pulled the fuel injector for that cylinder......and that is what I posted in my pictures.....the crud that builds up inside the "end cap" ......right at the spray end of the fuel injector.

Since that time, I have corrected the misfire, when it has happened, with the Berryman's B-12 Chemtool.
I think that it is a good idea to treat the fuel, say 2 times a year.
The Windstar seems to have an issue with building up junk inside that end cap at the fuel injector output.
I have tried adding a catch can to reduce the amount of oil vapor that enters the intake.....while still keeping the PCV system doing it's job of pulling junk out of the crankcase.
Even with that, and a maintenance dose of a detergent cleaner / lubricant to the fuel system, I find that the Berryman's a couple times a year helps.

Simply put.....I know that it works.

What it will not do, is clean the IMR plates or EGR ports, as the cleaner is in the fuel......and those 2 items are not in the fuel path.....so the cleaner never touches them.