Am in need of some help I have a 1991 Jeep Cherokee 4.0L and it seems like the first start of the day it will turn over then idle real low and die and it will do this over and over until I press the gas and hold idle at 1-2k rpm for 30seconds to a minute and then even then it still seems hesitant. My friends say it’s just because it’s an old vehicle and it’s cold out but I feel like that’s not the issue. It was 65-70 degrees out one day and it still did this issue any ideas on what it could be or where I can start. It does not do this issue after the first start up after being driven for a little bit unless it sits for awhile

 

If it has the original injectors, I would recommend changing them. It's entirely possible you have one or more sticking and not cycling properly. Just a guess.

 

Once it's warmed up and running, where is your idle speed?

Here are three things I would look at:

1. IAC (Idle Air Control). Sometimes just a good cleaning (easy job) will take care of this. Sometimes it needs to be replaced.
2. TPS (Throttle Position Sensor). This can be tested. Plenty of vids on YouTube.
3. Air Charge Temperature Sensor. I have no clue how to test this!

 

The ATC is simply a variable resistor that senses manifold air temperature by changing resistance. I don't have the time right now to find the values, but they are in the Haynes Manual.

 

How is your battery and connections?

 

This sounds like an IAC stuck in the warmed up position. Do you have a check engine light?