95 3.8 Windstar, Fuel or Ignition Problem from hell...

Greetings All,
Here's one that has me stumped, both symptoms started about 6 months ago and seems to be getting worse....
30% of the time while starting, it will surge between 300rpm and
1,000rpm, often stalling. When it gets in this mode, I have to hold the starter motor on while the idle hunts around, before it will idle smoothly.
100% of the time, while in neutral with part or full throttle, motor will surge between 1,000 and 3,000 rpm. If I feather the throttle just right, I can get it to hold maybe 3,000rpm steady, but any attempt to spin it faster, and it starts surging again. (almost feels like a rev limiter, but at 3K?) Most of the time when it does this surging, if I don't time the throttle right, it will stall on the down swing.
When the two problems above combine, the damn thing can be near impossible to start, as adding any throttle while cranking puts you in the 'Surge' mode, which results in stalling once you take your foot off the gas.
Here's the kicker, once you get it to idle, put it in gear and it runs fine. By "Runs Fine" I mean it will bark the tires off a light, Pull strongly to 5Krpm, cruise down the highway, sit patiently idling at a light, absolutely normal driveability.
These two problems happen over the whole range of engine / air temperatures, Weather conditions, planetary alignments, etc.....
Here's what I've replaced:
Plugs, Wires, Fuel Filter, Primary 02 sensors (ones in front of the cats..)
I have an OBD-II monitoring setup on my laptop, and nothing seems out of the ordinary. No codes are ever created, and the check engine light always stays off.
Throttle position sensor reports normal movement when engine off with gradual throttle movement.
Mass air flow looks normal enough, IE depending on throttle position and RPM, I get a value that passes the 'common sense' test..
When I'm in gear and driving, the system stays in closed loop mode (except during hard accelerations, which I think is expected)
Fuel pressure, with engine off, holds steady at 50psi over-night. While idling its near 25psi, and during the WOT "surging" in neutral, the pressure is steady at 50psi again. While idling, If I pull the vacuum line off the fuel pressure regulator, the pressure goes from 25psi to 50psi, which seems normal..
I have two suspect areas that have caught my attention, but I'm not sure what to make of them.
#1 In neutral, WOT, and the motor surging between 1K and 3K RPM, I can watch the OBD-II fuel system cycle between open and closed loop in time with the surging...
#2 Pulling a plug wire and attaching it to a grounded plug, the spark seem a little "wimpy". But it always has spark, even when the engine is surging.
I've even gone so far at to start un-plugging things, like the 02 sensors, MAF, MAP, Coolant temp, just to see if the symptoms would change, and they didn't...
Anyone have Any suggestions???
BTW, the van has 182,000 miles on it, and if its broke I fix it. Normally this isn't a problem as I 'KNOW' what broke, but this time I can't find anything wrong other than it isn't 'right' and its getting worse!
Thanks in Advance!
Take Care, James Lerch http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. Calvin Coolidge
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On Sun, 08 Feb 2004 02:09:35 GMT, snipped-for-privacy@no.spam.tampabay.rr.com (James Lerch) wrote:
|Greetings All, | |Here's one that has me stumped, both symptoms started about 6 months |ago and seems to be getting worse.... | |30% of the time while starting, it will surge between 300rpm and |1,000rpm, often stalling. When it gets in this mode, I have to hold |the starter motor on while the idle hunts around, before it will idle |smoothly.
I don't know. Is this a fuel injected engine? If so, you _never_ give it throttle when starting. Period. Why are you *feathering* when trying to start this *thing.* ????
Lg
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On Sat, 07 Feb 2004 21:32:05 -0600, Lawrence Glickman

Hi Lawrence,
Yea, its fuel injected. I also agree, no need for throttle while starting.
I was only attempting to 'feather' the throttle while it was starting as the Engine was bouncing between 'Starter motor RPM' and 600rpm (thinking the Idle speed motor might have been acting up.)
It was when I first tried the 'feather' trick while starting one day, that I found the surge between Idle and 3000rpm symptom. (very weird..)
Take Care, James Lerch http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. Calvin Coolidge
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On Sun, 08 Feb 2004 04:58:04 GMT, snipped-for-privacy@no.spam.tampabay.rr.com (James Lerch) wrote:
|Hi Lawrence, | |Yea, its fuel injected. I also agree, no need for throttle while |starting. | |I was only attempting to 'feather' the throttle while it was starting |as the Engine was bouncing between 'Starter motor RPM' and 600rpm |(thinking the Idle speed motor might have been acting up.) | |It was when I first tried the 'feather' trick while starting one day, |that I found the surge between Idle and 3000rpm symptom. (very |weird..) | | |Take Care, |James Lerch
Sight unseen, I am going to guess you have a vacuum leak somewhere. Hose rotted through somewhere. Have seen something like this before.
Check yer hoses. Too much air is getting in somewhere, causing the lean condition.
Lg
|http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site) | |Press on: nothing in the world can take the place of perseverance. |Talent will not; nothing is more common than unsuccessful men with talent. |Genius will not; unrewarded genius is almost a proverb. |Education will not; the world is full of educated derelicts. |Persistence and determination alone are omnipotent. |Calvin Coolidge
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Hi Guys,
Did some more research this AM, and its rather puzzling..
WIth an O-Scope on an injector wire, on the down swing of each 'surge' the pulses for the injector stop... (just like the computer said "No, you don' t need no fuel".....
I've also been able constrain the problem a little better. The surging only happens while in OPEN loop mode. If I let it idle long enough to go into CLosed loop ops, and am gentle while applying the throttle, it won't do the surge trick.
However, if I go WOT quickly (while still in neutral) I see the computer flop over to OPEN loop, and at that moment the pulses to the injector quit. As soon as the computer flops back to Closed loop, the motor comes back to life.
The cycle of the surge is directly related to the cycle of the Open / Closed loop event....
Another interesting bit, when I'm in gear and driving, the computer never seems to leave Closed Loop Ops, so everything runs ok..
SO, what changes between Closed and Open loop that would cause the computer to shut down fuel supply?
As an aside, I also have an attachment to clamp onto a plug wire so I can observe the ignition wire behavior on my O-Scope. During the surging, the ignition system seems fine....
Take Care, James Lerch http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)
Press on: nothing in the world can take the place of perseverance. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. Calvin Coolidge
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