My '87 3.9L is having issues like this. It stalls reliably at lights, and likely if slowing down, even on the highway, just slowing up a bit for traffic and it dies. It is starting to really annoy me. It stalled three times this morning, once at a complete stop of traffic on highway, took a couple tries to restart, probably annoyed people once traffic was moving. The next time, i slowed up a bit, but was able to restart it while still moving, didnt cause problems. The third time, i was trying a technique; Putting it in neutral, braking as usual and reving the engine to keep the RPMs up. It seems directly correlated with electrical, if headlights are on, or climate control blower(recirc, heat, cool, doesnt matter) The alternator is new, but could be tightened a bit. It does it worse when the engine is cold, but still has issues in 90 degree weather after driving 10-15 miles. I am thinking a fuel pump issue. The original, in-tank pump is bad, the person before me installed a secondary one on the outside, but in-line(presumably to avoid opening the tank, saving money. The original worked for a while again, but it started hesitating, like i was running out of gas, so i turned on the secondary(i had previously installed a switch, no need pumping extra fuel if the normal pump works). It ran good for a while, but it is now doing this crap. Could it be something with the carburator? Or maybe a clogged fuel filter? It has a minor transmission problem.
1 year old alternator, battery, and voltage regulator, 2 month old distributor cap/rotor, and plug wires, 4 month old plugs, new pcv filter, 7 month old air filter. 4,400 miles into an oil change with top-of-the-line oil filter and fully synthetic oil. 5w-30 if i recall? Whatever was recommended for the mid-colder months.
3 speed? automatic. (could be a 4 speed, but i only feel it shift twice, 1-2, 2-3, i never feel 3-4, and there is no visible overdrive feature.
I got some new wheels with lower profile tires, and have been having fun with the better handling, drifting in parking lots and taking turns a lot faster, if that might have caused damage, i know i rev the engine pretty high when drifting.
Any ideas?
Sorry if some of that information is not necessary, but i just wanted to be thorough.

 

Since it is carbed I'm doubting there is a intake pump, but I don't know enough about the early years. Most carbed vehicles had a fuel pump connected to the engine block.

Tons of possibilities. Yes possibly the carb, or bad fuel pump or bad lines or electrical since you said the lights and radio die with the engine.

There is a post on an 87 where there is a 9volt battery that was dead on his truck, he replaced it and it ran perfect. Try that, here is the post read threw it all, tons more tips through out the entire post.
https://dodgeforum.com/forum/1st-gen...talling-5.html

 

Thanks for the help, im going to go try that.

 

I've been through about every inch of my truck before i found that 9v, its located on a bracket about an inch above your parking brake, no need to take anything apart just slide it up off of the bracket, it will have a red connector on it, the opposite end of the plug there was a black cover for my 9v had a white sticker across it i had to peel off, mine had he same stalling for no reason, and it would sometimes feel like it loses power but not completely, just chugs pretty sure we have the same vehicle so if the 9v doesnt work i can direct you towards some other inexpensive parts that added to my problems. Hope that 9v is your problem and maybe i enlightened the few still brave enough to drive the '87 lol.

 

I mentioned to my dad that this might be the problem, and he looked at me like i was crazy. He couldnt contemplate a 9V battery in a vehicle. I have seen it in mine, and am near certain every vehicle has one...
When you mean it would lose power and chug a lot, you mean the way it hesitates when you are running out of gas? Mine did that a while back, so i turned on my secondary fuel pump and it solved it. Thats why i was suspicious of it. havent gotten around to changing the battery, it didnt show symptoms today, its kinda off-and-on, so i want to do it one a day when it is, so i know if its fixed, or not symptomatic.
also, i went to change my new tires out, since they dont fit quite right and were too wobbly, and ended up with a loose lug stud, and hence a stuck lug nut. Been working on that for 8 hours with no actual progress other than the tool i need will be here tomorrow.
They say ford = fix or repair daily... as much as i love dodge, and my truck, i think my truck is a ford, disguised as a dodge, small problems, but something every day.

 

Mine would be about once to once a week, i guess your module runs in a "limp mode" when the battery is dead, just take it out and touch it to your tongue, if its dead you need a new one anyways. The chugging would be like my carb wasn't getting fuel, id put it in neutral and restart the engine and id be fine. It's been about two weeks now since i replaced the battery and not 1 problem whatso ever, and I've seemed to increase my gas mileage by a considerable amount once that module can save the adjustments it makes to your engine. But I'm not positive on that module, i believe its the early stages of the computer that runs cars nowadays.

 

Are you burning up gas like crazy? because the only way your mechanical fuel pump on the side of the engine goes bad is if the diaphragm gets ripped and it trickles gas out of a hole when it does. when myne was running bad extra gas always seemed to fix it, i had my adjustment screws were almost 4 turns out to make it run right, you do have the OEM holly carb right double barrel? i was getting like 2 miles to the gallon before i found that battery now im getting like 10 miles to the gallon, you could look in my intake manifold and see little puddles of gas before... Now its bone dry and running great.

 

oh god! 10 miles per gallon?! how do you live? I swear i can pull off 26 if i try real hard, but i average 17.5mpg...
i will definately change that battery as soon as possible, every mechanical part is stock, so yeah, the holly. I have my idle speed backed out to save gas, but lately i noticed my exhaust smells really rich, ima take a glance at the fuel/air mixture tomorrow in the light.
try upgrading your spark plugs, distributor cap/rotor, and a new air filter, and get some quality oil. I guarantee you can pull that up to at least 15mpg for under $70. Want to get more, get a tonneau cover, and vortex generators, cover is about 250, and vortex generators 20. thatll pull you up to 19mpg at 55mph, go 40, and you can pull off 24 easy, turn off the engine for long lights, put it in neutral and coast when possible and accelerate as if you were a semi, very slow, and 26 shouldnt be hard.

 

My 87 dodge dakota 3.9 l automatic stalls as soon as i go on highway. Starts fine sometimes, put it in gear and then about 20 secs down road it starts to sputter then die. totally stumped,and we dont know what else it could be. Put new fuel pump on it still no fix. Any info would be appreiciated
Thanks

 

so it happens a lot when you slow down, as in taking your foot off the gas pedal?
Idle speed is dropping too low, perhaps, or fuel mixture is not correct for conditions.
Check for vacuum leaks, especially around the base of the carb, and where the butterfly shaft pivots on either side of the carb, and base of the spacer. While it is running, spray some wd40 around those spots and see if idle speed changes. Make sure all you vacuum operated devices are working and not leaking...
Also, low battery can affect the computer whicn will affect ignition timing.