I have a '95 Explorer, V6, 4x4, "X" Vin, with a stalling problem. There is an occasional miss, and at low speeds, roughly around 1500 - 2000 rpm, the vehicle will often stall. Usually when it is decelerating.
We had major miss problem which we seem to have cured by installing a new EGR valve. But it has not touched the low speed stalling.
So far, we have replaced the MAF, IAC Valve, EGR position sensor(twice), throttle position sensor, O2 Sensor, and now the EGR valve. While the engine seems stronger now, it still has a bit of a miss, and the low speed/deceleration stall.
I am begining to think Timing chain, which I can fix. However a location repair shop insists that my engine has a 4 chain timing chain set up, and that is something I don't want to mess with. I thought my engine had a simple one chain up front system.
Is there anything I might have missed or does any one have any ideas on what might be wrong?

 

Sometimes we overlook the simple things. I noticed you didn't mention the fuel filter !

 

Fuel filter has been replaced, as has the fuel pump. Both at about 2 years ago. Vehicle has 200,000 miles, and the engine seems to be in good shape. But, it has had this stalling problem for several years, but now seems to be getting worse.

 

You're gonna shoot me for this one! Since you have had the stalling problem and its getting worse, In the trade there is an expression, " Let it develop" and it seems as though you are making progress!
Seriously, Did you have an opportunity to verify that the EGR is functioning properly?
Have you been able to obtain any codes from the ECM? Also A very thorough check of the vacuum hoses and intake system might reveal something that was skipped over in the past. When was the last time you checked /replaced the PCV valve?

 

From the symptons the car was showing a few days ago, we deduced the EGR was stuck open. We replaced the EGR valve, and those symptons went away. It hasn't run this smooth in a while.
However, we still have not fixed the stall on deceleration. The codes are showing 173 which is "HEGO shows always rich", and 177, "HEGO shows system always lean(left)".
If those are the O2 sensors, they were replaced in March.
Check Engine light is not on.

 

We need to confirm the codes you posted. My info states the HEGO are both showing RICH. What this tells us is ; The computer is trying to correct a lean condition that could have a few causes, vacuum leak, EGR system etc.
Do you have access to a scan tool that will provide "serial data"? With this you can observe just what the o2 sensors are doing and what the ECM is doing to respond to the info from the o2 sensors. Please see if we can get the codes info clarified , then we can move on, OK, Thanks ,,,,hanky

 

Hanky, I will try to get "serial" data. Currently I am using a small hand held OBD1 scanner. There was a vacuum leak that was repaired about 6 months ago. Intake manafold gasket has gone to pieces. The first repair shop fixed the gasket, but in the process of replacing the manafold, they caught a line of some sort under it, causing a second leak. Which was repaired by a second repair shop.
I have tested most of the vacuum line junctions with the time old method of spraying with Carb cleaner, and I am unable to find a leak.
The code reader is actually showing these codes....173,177, 646(trans codes).

 

There are times I had to block off some vacuum lines while checking others with a vacuum pump. We also learned when some mechanic says I checked this and that we recheck to satisfy ourselves and sometimes find they missed one. That is why I ask that you check everything you can see and get to, because until you do this, there's always that little one that got past us. Something is causing the ECM to increase injector on time giving that rich code you are getting and the ECM usually responds to the signal from the O2 sensors. What did the spark plugs look like? Do they show any evidence of excess fuel? How was your mileage? If the mechanic that repaired the intake gaskets used the wrong adhesive/sealant he could have contaminated the 02 sensors and this could drive you up the wall thinking they were just replaced and should be fine.
I could always suggest you keep driving and don't decelerate and therefore your stalling problem would be unnoticed, huh?
It's important that you don't lose your sense of humor! ,,,,,,,,,hanky

 

Thanks, Hanky. This is my son's car, and this morning he came in and said the Over Drive light was no longer flashing. It had been flashing for sometime. Probably from the 646 code.
He also said that the car now seems to really have some get up and go. Lots of power. We hooked it up to the code reader, and NO CODES!!!!!!!!!!
I can't believe that just changing out the EGR valve would do all that. But, we are going to continue to monitor it.
To answer your question about the spark plugs and milage. We had pulled the plugs, and they didn't appear too bad. But his milage has been way down for a while.
Though he is still having a bit of problem with the stalling on deceleration. I am wondering if a worn/stretched/loose timing chain would cause that. Since it does have 200,000 on the original chain.

 

The fact that the vehicle has plenty of power would lead me to believe the timing chain system is not the cause of the stalling problem.