diagnose this

You've replaced the cap/rotor? One real possibility is moisture in/on the cap/rotor causing a mis-fire, when the engine warms the moisture evaporates, then re-condenses when the engine cools.

(OK, I hope this engine does have a cap/rotor!)

Check the fuel pressure regulator.

--scott

It isn't, "the moisture evaporates, then re-condenses when the engine cools."

These are noted for vacumm leaks at the plentum, blown head gaskets and fuel pressure problems. All of which will cause your symptoms. You need to diagnosis it, instead of guessing.

Cold Start injector?

On Mar 20, 12:18 pm, Hachiroku $B%O%A%m%/(B

Doesn't have one.

Thanks, pal...shoot me down in flames! ;)

I know from my Toyotas that a leaky CSI can cause this same problem.

Are there any codes? MIL? These things are very sensitive to grounds... voltage drop the grounds and make sure none are above .050 volts. My gut instinct says its a bad o2 ground. HTH Ben

Cap and rotor? Are you familiar with this engine?

Codes? Is it using more oil than normal? Check plugs #2 and #5

I thought my "(OK, I hope this engine does have a cap/rotor!)" disclaimer was enough to say that it was general advice. I deeply and humbly appologize if I caused you distress, but I've seen the problem I described before and figured it was a good guess.

Oh, don't get your hopes up.... you haven't caused any distress but you have been a source of amusement.... One of the big problems we see stems from not knowing what we are speaking of...

I don't tell people how to fix their Dolby 5.1 surround sound systems because I'm not familiar with them.... I don't tell them how to cure diarrhea because I'm not a doctor and I'm not familiar with the concern...

Silly wild ass guesses are silly wild ass guesses - while they might make you feel better, they do little for anyone else that is unfamiliar with their system...

Nothing that turns on the check engine light. Guess I'll have to run it down to autozone and see if there are any hidden codes their scanner turns up. Never uses oil. I'll check the plugs.

It's a good thought but it is distributorless. It could be that the wires aren't very good I suppose, they are new Bosch and I've never had trouble with Bosch before but there's always a first time.

I am trying to diagnose it by starting with some educated thoughts.

A couple people have suggested fuel pressure regulator. For some reason it's been getting somewhat BETTER gas mileage lately, which perhaps is a symptom of low fuel pressure? And the popping, missing perhaps is also a symptom of low fuel pressure? My fuel pressure tester is loaned out so I will have to get it back and take a look.

Not sure, but a rich mixture should throw a code, probably through the

1. No experience with Ford, but the only time I had that bucking on acceleration new injectors fixed it. Rough idle in drive at a light too. That was a 2.8 in a Celebrity. Think I had my mech replace all 6 of them, and it cost me about 5 bills. I'm a little hazy on it, but it fixed it for good and I drove it until about 190k miles before rust ate it up. Did the injectors at about 140k miles I've tested injectors (Deltac II's I think) on a couple of my other cars with an ohmmeter and always got readings all over the place, but within the spec range. The ones that came from the car that was running good (for example I pulled the injectors on the cars I sent to the boneyard due to rust) worked fine in the trouble car, though you couldn't tell from the ohm readings. Just a thought.

--Vic

I had the same set of symptoms on a '99 Explorer.

It took almost 2 years, and $1,400, of replacing/repairing one thing another until the "upper and lower intake manifold gaskets" were replaced. The mechanic tried that after allowing butane or propane to be released in various places as the cold engine was idling, and the fact that the engine speeded up when the butane/propane was released in a certain place suggested to him that there was a leak there, and that the leak was allowing the butane/propane to be sucked in and burned with the gasoline. His theory was that this leak was only there when the engine was cold, and that when it warmed up the metal expansion closed the leak; when the engine was cold, and the leak was there, additional air was being sucked in and diluting the gasoline/air mixture so much that the missing and stumbling was being caused.

(What I'm reporting here is my experience, and what my mechanic told me. I have no automotive skills, and thus offer this only for consideration.)

Best regards to all.

============================

This is the standard procedure for finding vacuum leaks of all sorts. And if you encounter rough running problems that seem random, one of the first things to do is to start looking for vacuum leaks.

It is an excellent offer, though.

--scott

Just curious, but did you have intake manifold gasket leaks and NO coolant loss or white smoke at startup? I'm having trouble imagining a manifold gasket leak without coolant going somewhere, either inside the engine or outside. Unless it was ONLY the upper gasket that was leaking. Seems kinda unlikely.

Yea, well, if it wasn't for Hayne's and this newsgroup my Explorers would have been in the junk yard many years ago.