[Vcwdldva]

1989 w. the 4.0L Automatic.

It only does this while the engine is cold. Turns on fine. idles fine. Give it gas its fine. But this is where it almost stalls out every time.

Give it gas, it revs up. Left off gas and give it gas again, it almost stalls out every time, but then revs up before it dies. Only will do this a couple of times, only while it is cold.
I just replaced the EGR thinking that it could be the issue. I had the vacuum line unplugged because if it was plugged into it, it would stall out if you were not giving it any gas no matter the speed. So had to replace that for safety + emissions and was hoping that it would fix the cold almost stalling out issue it has atm but it did not.

[HawksBurnDown]

Meh...

Seafoam fixes everything. Unless it doesn't fix something. Then a mechanic fixes everything.

[Vcwdldva]

Might try it out. Got a bottle of seafoam and only put it only in the gas tank. Should run it through the vaccum lines. Maybe put a touch in the oil before I change it out. My truck could use some as well.
Just sucks cause that stuff is like $10 bottle now.

[HawksBurnDown]

Might try it out. Got a bottle of seafoam and only put it only in the gas tank. Might run it through the vaccum lines. My truck could use some as well.
Just sucks cause that stuff is like $10 bottle now.

It cleans everything out wonderfully actually.

Pour 1/2 - 3/4 of a bottle into a tupperware container, then slowly let the vacuum line draw it in until the engine bogs itself down and stalls out. Let it sit for 15-20 minutes then start it up and give it some gas.

My 8 year old truck (at the time I did the seafoam) spewed huge clouds for a solid 5 minutes. Drove it for another 20 miles to let the gunk fall into the oil then had an oilchange. Made a huge difference in fuel economy and engine response.

In response to your original question, mine did that for a time and it was actually a vacuum leak that was the problem. Replaced a hose and the problem went away. Constantly revving up and down, would stall if you took your foot off the pedal. Pain in the ass.

[oneliRafmeene]

Another vote for the crank sensor,since it only does it while cold.

[Fuerfsanv]

Or a fuel injector...but more than likely the sensor.

[itititit]

Did you check the flux capacitor?

[mQb0aVZe]

1989 w. the 4.0L Automatic.

It only does this while the engine is cold. Turns on fine. idles fine. Give it gas its fine. But this is where it almost stalls out every time.

Give it gas, it revs up. Left off gas and give it gas again, it almost stalls out every time, but then revs up before it dies. Only will do this a couple of times, only while it is cold.
I just replaced the EGR thinking that it could be the issue. I had the vacuum line unplugged because if it was plugged into it, it would stall out if you were not giving it any gas no matter the speed. So had to replace that for safety + emissions and was hoping that it would fix the cold almost stalling out issue it has atm but it did not.

Clean the IAC stepper motor and passages.

The IAC should be on the throttle body, it controls the throttle blades for idle control. It may not be reacting fast enough when coming down, if its lazy it won't react fast enough to keep the engine idling. When cold the motor will be slower than when warm.

You can remove the motor and spray the pintle with carb cleaner, you can also spray it into the passage to get rid of gunk and carbon build up which might be impeading the motor.

If that doesn't fix it the issue is something else, or the motor is bad. But the only way to truly diagnose a bad stepper motor is to look at the IAC counts using a scan tool.

[Vcwdldva]

mine did that, it was the crank sensor that's on the drivers side bellhousing..

was cheap like $50 for the sensor

Yeah, I have heard that this sensor causes problems. Though when I found it, it looks impossible to replace without doing major work.
I was going to get one cause they are only $32, but thought "I doubt I can easily change that"

Clean the IAC stepper motor and passages.

The IAC should be on the throttle body, it controls the throttle blades for idle control. It may not be reacting fast enough when coming down, if its lazy it won't react fast enough to keep the engine idling. When cold the motor will be slower than when warm.

You can remove the motor and spray the pintle with carb cleaner, you can also spray it into the passage to get rid of gunk and carbon build up which might be impeading the motor.

If that doesn't fix it the issue is something else, or the motor is bad. But the only way to truly diagnose a bad stepper motor is to look at the IAC counts using a scan tool.

I might dig into the throttle body area. I have removed the IAC and it was clean, and clean inside. I went a head and cleaned everything, but seemed like it did little. I would have just replaced it, cause I had rather do that, but the stupid thing costs $60.
Its hard to go around and replace all the senors/valves when I could easily spend $300 on them. On my S10, most major senors/valves are just $20~$30.
Already spent way too much on the EGR valve.

[Loolasant]

See if there is room for me to work, but I put seafoam in the jeep today through a vacuum line.

A lot of smoke was coming up through the engine bay. Got underneath it and there is a rather large gap between the manifold and downpipe. See if I can tighten those bolts down.

Also a good way to find your vacuum leak.
Not really sure if this did anything but make a lot of smoke! Gotta be horrible for the environment! I have seen videos where all kinds of cr/p blew out of the exhaust, but nothing on both the Jeep and my S10. My S10 did smoke a heck of a lot longer than the Jeep did.

[Vcwdldva]

I wasn't sure if this stuff was going to work, or was just a $10 gimmick running it through the vaccum lines.

Well apparently, this stuff really does work. The Jeep no longer stalls out when I first turn it on and give it gas within the first 20 seconds or so.
Im not sure if the Seafoam did it, or other tinkering of mine did it, but my S10 engine light is gone for good (hopefully.)
I do believe it was my CO2 sensor which has fused together with the exhaust and was causing me to get 14mpg and on the verge of failing emissions. Im back to 21mpg so hopefully it was just clogged and is now clean enough to keep working properly.