1998 Windstar problem

I have a 1998 Windstar, 3.8l, with 200,000 Klics or 125,000 miles. I have a problem that I think the beginnings can be traced back several years or maybe unrelated. 3 years ago every once in a while on a very hot day, coming off the highway and stopping at a light the van would stumble for maybe 5 seconds then settle down and run fine. Over the years it's become worse it progressed to not so hot days and coming off the highway, and then cooler days coming off the highway. Also running around town and stopping at a store for 5 minutes every once in a while I would come out and the van would stumble for 10 to 15 seconds and then settle down and run fine. This has been getting worse, now after the engine is up to operating temp the van misses and runs very rough. When the engine is cold it run perfect, doesn't miss a beat. 2 codes come up, 302 (misfire cylinder 2) comes up consistently, and code 171 (lean code) comes up once in a while. I have been diagnosing this van for several months now and am becoming frustrated. Results so far - Vacuum is steady 21.5 PSI - I have changed spark plugs and the 1 wire for cylinder 2 - Fuel pressure is only 24 PSI (with my questionable gauge) however when I take the vacuum off of the regulator the pressure goes up to 35 PSI but the van still runs rough. I believe it needs 25 PSI. - I have checked the ohms in the coil and it seems within specs. - I cannot find a vacuum leak - I have pulled the vacuum for the EGR and the engine still runs rough Not sure what else to try, I know that there was an issue with intake gaskets on later models and have not ruled that out, but would like conformation before tearing it down. Becoming a little frustrated so any help would be appreciated. LWolffe

Check the vaccum line that goes from the top of the upper intake manifold to the PCV valve.
After all these years, it could be breaking down.

The same is true for the other vaccum line, but the PCV line.....the soft rubber parts break down from the oil exposure over the years......

Another thing to try is replacing the coil pack.....they seem to fail more often on newer windstars than on the older ones, but the way that they fail is that the epoxy body cracks.....and they arc through the crack.
THIS is something that you are not likely to measure, as it is high voltage jumping a gap.

On my '96, I found that running Berryman's B-12 Chemtool (in the metal can) would help with the increasing missfire that I would develop.
I think that they had the issue resolved by '98 though.
The issue was the development of deposits inside the fuel injector end caps.

Other than that.....make sure that you are up on all the routine maintenance items, including the fuel filter.