I know this has been asked quite a few times but the issues were not exactly the same as mine, so I felt the need to post this thread.

I've got a 1989 4.0L, recently replaced the thermostat/housing, serpentine belt, and a few other things. Everything has been running smoothly up until yesterday afternoon. Around 3:00PM, I started the Jeep up. It took a little longer than usual to fire up, but it fired nonetheless. Less than 100 yards later, my Jeep just died. The first thing that came to my mind was that I ran out of gas, so I fired her back up and she drove back home fine. I later topped off the tank, it only cost $16.95 so I assume I wasn't out of gas to begin with. It drove home fine that night.

This morning, I cranked it up fine. It turned over smoothly and took the normal time to do so. Put it in reverse and noticed the RPMs fluctuating anywhere from 50-800, and then quickly dying. I fired it up again and drove down the road. As I was driving, it was fluctuating again from 50-800 but it never died again.

Does anybody have a clue as to what this could be and what I'm about to get myself in too?

TLDR Version:
Idle fluctuates at 50-800, sputters, dies.

 

CPS, TPS, IAC, check fuel and spark components, pressure test each cylinder.

 

If I cleaned the IAC and TPS, as well as changed out my plugs and wires could that potentially correct my problem?

 

Yes and no, sometimes the sensors NEED to be replaced, sometimes they can just be cleaned.

Do plugs, wires, cap, etc if you havent in a while.

 

Forgive me for being Cpt. Obvious on this one, but is your throttle body really gunked up? A few times I've seen almost these exact symptoms, low idle, stalling, etc, and after spending quite a while checking a bunch of stuff, cleaned the throttle body and it fixed it right up.

My theory is always start with the simple stuff, forgive me if you've already done it.

 

cps fixed it for me, when it would get heat soaked, after a few minutes of driving, then parking, then starting again it would do it. Cps was getting heat soaked....

On another note, the cps fixed it, BUT cleaning the IAC afterwards made it even more stable of a idle at cold temps.