1999 Windstar Rough At Idle And At Higher Speeds

I've been researching this forum for the last couple days and have found a lot of great information. Looking for some help. My wife's 1999 Windstar runs rough at idle and at normal "around town" speeds (35mph-50mph). I'll start out by saying that I've replaced just about everything. I was getting the infamoust P0171/P0174 codes. I've done the TSB for the isolator bolts, valve cover, etc. and those codes have not returned (good thing) but it still runs rough (bad thing). I've replaced the MAF, IACV, plugs, wires, coil pack, fuel filter, O2 sensors, PVC valve, PVC hose all to no avail. I put a can of Seafoam in the air intake (through the PVC hose) and in the fuel tank. That did improve the "pickup" but it still runs rough. The biggest mystery is with the fact that it's running so poorly there are no DTCs! In the last couple days my wife has noticed a "rotten egg" smell from the exhaust. The only other things I can think of (that I haven't replaced) is the catalytic converter and the fuel injectors. Any help would be appreciated.

Did you use MOTORCRAFT double Platinum spark plugs......Bosch are know to be a problem in the Windstar.

Try running some fuel system cleaner through....Chevron Techron (2 bottles if they say "up to 12 gallons").....do treat 2 tanks back to back. You may need to remove and clean the fuel injectors....inside the cup over the spray end.....if they fuel system cleaning does not work.
Crud inside the cap over the spray end of the fuel injectors was what caused my elusive engine miss this past summer......would not come out with fuel system cleaning.....I had to remove each injector and spray cleaner inside that cup.....and the crud came right out.

As you have to remove the upper intake manifold to get to the injectors........make sure that all 6 EGR ports are clean.

Make sure that the Check Engine Light comes on for a short time when you start the car.....just to be sure that it is not burned out.

Thanks for the info... I'm going to tear into this this weekend. What do you recommend for the cleaning solution? The Valvoline stuff?

Sorry... I typed Valvoline but mean Chevron.

After spending 5 hours tearing into the WS again today I have success. I cleaned the fuel injectors with a fuel/Seafoam mix, replaced the injector o-rings, and put the motorcraft double platinum plugs ($58.00 for the set!) in. All the hesitation is gone (for now). I double checked the egr valves and they still looked good from cleaning them about two months ago. The only problem I had was that the retainer clips on the fuel injector wiring harness broke on every injector. I'm happy to be done with this problem... now just waiting for the transmission to go. I'm at 90,000 miles.

Forgot to mention - thanks to wiswind for the tips on the injectors and the plugs.

Thanks for the feedback.
The Motorcraft plugs are carried at Autozone.
For my '96.....Stock code #686.....on their computer. The box has both numbers....Last I looked....they were just under $5 each.
My local Autozone was sold out....so I went to my dealer. The parts guy said...."That's too much.....I'll sell them to you at $5 each".
They most often knock the price down on what they sell me.
But....even at $58....it's not bad as they will last another 100K.

For the tranny, make SURE to change out the fluid at LEAST every 30K miles......21K miles for "severe" service. I would also recommend an auxilary cooler.
I have a Derale 17,500 GVW cooler on mine.
I found coolers for very good prices at www.bulkpart.com I did not buy mine from them.....as I just found that site recently.

Hopefully I won't need to worry about the plugs for a while and frankly if it would have fixed the problem sooner I would have paid twice that.

I have been pretty good at keeping up with the transmission... it's probably time to do it again and I'll take a look at the coolers. Thanks again.