Finally, I had the notourious hesitation while the car was under load below around 3K. Here is a snapshot.
Hesitation started after replacing OE plugs only with Autolite pp's. I blamed plugs wires then switched from OE to 9MM, no change. Then I replaced coil pack, fuel filter cleaned TB and KKM intake, performed UIM/LIM cleaning, nothing changed. After tolerating for a while I switched plugs again thinking maybe a faulty plug, no change. After many hours after tinkering around with secondaries, vaccum tubes, etc all seemed to be operating normal. I was leaning toward fuel pump as my next attack. While surfing this site as I have done before I happenned upon a post by "Kennard" who very enthusiastically fixed his hesitation in a zetec by going back to the Motorcraft plug. Well, I finally made the trip to the dealer and I can't beleive the difference. smooth as butter. I highly recommend to anyone with a similar problem to get the Motorcraft plug. I guess I've read on here that Autolite makes the Motorcraft plug or vice versa but they do look very different at the electrode tip. I have a 99 2.5 SE my plug was AGSF32FM they are single plat but I'll gladly switch em out a little earlier than the pp's. They are performing extremely well in my Duratec. Hope this helps anyone with this problem.
