Engine stalls while driving why?

1991 Ford Explorer 6 cyl Two Wheel Drive Automatic

My explorer won't stay running when cold and bogs down while driving and giving alot of gas. The check engine light comes on and off.

I got 172, ho2s lean, 543, secondary fuel pump fault and 556, primary fuel pump fault

Engine Mechanical problem
1991 Ford Explorer 6 cyl Two Wheel Drive Automatic 230 K miles

Long block recently installed (6 mo.) By Thunderbolt in Houston. Runs great, however, two days ago, after driving for about an hour, vehicle was parked. A couple of hours later, vehicle would turn over, but not start. The next day, engine started and ran smoothly for about 20 minutes and then the engine shut off as you would normally turn it off. About an hour later, engine started up and ran smoothly for about 15-20 minutes and then it stopped running as if shut off. I changed the fuel filter with same issue. I suspect the fuel relay or the inertia switch/wiring. Fuel pump is original, but seems to be working fine. 230,000 miles on frame.

What would cause the truck to stop running all of a sudden, check engine light came on aftering stopping at a stop sign and then when I went to give it gas to go it just stopped and cut off. It still has battery power, no other lights came on except for the ones that come on when you first start the vehicle. Does it have something to do with the fuel injection, or pump.

This turned out to be the ECT [Engine Coolant Temperature] sensor, according to my Ford dealer service department which was reading -20 on a 40 degree day. For those of you experienced enough how long should it take to diagnose this? What is a fair charge in diagnostic hours? Also, how long would it take to fix? According to the Haynes manual you have to remove the upper intake manifold, but it also states that it might be accessible if the thermostat housing is removed. If this is the case, shouldn’t this be an easy repair? It will start ok, idle high for 20 sec and then stall. Once it stalls it will not start up easily again - just cranks and cranks. If I hold the pedal all the way down I can get it to start very rough and then I have to keep the idle up or it will stall. Once forced into gear it will not stall and has all the power I ask it for. But it idles too high and surges while slowing down around 20 MPH. I can rule out the IAC and MAF and EGR valve. It will always start right away after resting over night. Surge also happens in neutral idle when you pulse the trottle. It revs up and hangs there too long before slowing down again. It will also stall when I take it out of gear. It will rev up and then fall to a stall. There are no OBDII codes returned. By the way this all began rather suddenly †drove 10 miles to store one day, went in, came out, started car fine, it stalled, then would not easily start again †before which you would not know anything was wrong. Any Ideas?

Things I think it is not and why:
- Fuel pump - it never loses power once in gear.
- IAC - I tryed a new one
- MAF - I tryed a new one
- EGR - took it out tested valve and blocked pipe while running with no change.
- Vac Leak - because it is so hard to restart?

Things I think it might be and why:
- Vac Leak - high idle : no symtoms during open throttle.
- O2 sensor - I do not know if there were codes for the O2 because now the OBDII for O2 is not ready because I disconnected the battery. I believe however that there were no codes when the O2 was ready

Comments very welcome!

It has run great. While driving under normal conditions the engine just shuts off, all other items contiune to work electric A/C ect. It almost as if there is no gas in the car. The engine will turn over but just wont start, after a few minutes the engine will start and drive again, but after a few more minutes of driving it will die again. Its a never ending cycle, runs, dies, works again after a few minutes, dies again. It does this when coasting, at a full stop, accelerating stopping, not at any particular time. All guages are in line, gas, elec, oil, I cant seem to find the problem. Any ideas?

Sounds electrical to me. Check for spark at the plug(be sure to ground plug). If no spark, be sure the fuel pumps kick in when you turn the key to the "on" position. If the fuel pumps don't click on, check the relay. If relay ok, and fuel is reaching the fuel rail, then I would guess the problem is in the primary electrical circuit to the ignition. Could be a coil cutting out, or ignition system problems such as stator, or losing PIP signal. Have the codes scanned for a lead.

My 1998 Ford Explorer sometimes stalls at stop signs or when pulling into a parking spot. It usually starts right back up again. When I had trouble getting it to stay started, it worked better in reverse. I had the fuel filter replaced and new spark plugs put in. I changed the air filter and cleaned the air sensor. It seems to stall less often when the fuel tank in near fuel. The SUV will stall once or twice and then not again for 2-3 days.

My truck is stalling when braking. I can drive the truck fine once it is started as long as I keep the accelerator pushed at the same time I am breaking. Sometimes it is so hard to start and other times it runs fine. We have replaced the throttle control and that helped for a while. I drove this car to Florida and it was fine all the way there. When I went to drive it the day after we arrived it stalled. I put some Fuel system cleaner in it and didn't have another problem and drove it all the way back to Indiana. It is 2 weeks later and it is stalling again.

This truck is important to me b/c it is my only mode of transportation since I am in graduate school.

I routinely maintain this vehicle, but today the truck started like normal, idle raised twice, then just slowly stumbled and died. I tried to restart but it would not turnover. I tried it on and off and nothing. Finally it went and did the same thing. After fussing with it, I finally got it to go and it drove fine.

The battery, starter are good, I even tried to replace the ignition coil. But that was fine.

No idea. Makes no sense unless it is a sensor, but there is no way to check b/c it has no computer hookup.

How do I solve this? What could it be?
Thanks.