So I started having this issue about a month ago and cannot seem to figure it out on my own. I have a 1988 Jeep Cherokee with the 4.0. When I start the Jeep all is well it drives great but if I let the Jeep warm up and turn it off it acts like it doesn't have enough power to turn the motor over. I have tested both the starter (Brand new) and the battery (Optima) and both are performing great. I really cant think of a reason the engine would get so much harder to turn over when hot that I have to let it cool to under 140 degrees before I can turn it over again. I am thinking a sensor of some sort but I don't even have an idea of where to start.

TLDR
Jeep wont start when hot/warmed up but runs fine and starts any other time.

Have you checked the oil level? What kind of oil pressure does it hold at idle and when driving?

High resistance in the wiring.

Yes just changed the oil last week, Oil pressure is about 65 at start and 40 hot.

Then it has to be either battery cables/ground straps or your starter or battery. Just for my curiosity have you checked your oil?

I do have my electrical ran through a cut off switch that is inside my cab so could the increased cable length and heat adding to the resistance cause this?

Yes I checked it the day of and a few days after the oil change last week and it has been a stable amount and of good color as well.

Not real good on electrical, still say ground or cables. Starter could be bad enough that when hot it doesn't get enough juice.

Those were some of my first thoughts I have all new battery wires and wire to the starter, and it is a new starter as well since I thought the same thing about the old one when this first started. My grounds I pulled off and cleaned and reattached as well about 2 weeks ago thinking it might have been those.

Sounds like you need a load test done. Get the truck to operating temps and get a battery draw test done. It will tell you if the battery is up to snuff or if the starter is pulling more amps than the battery can provide.

OK I will try that tomorrow on my day off and see what happens. But I have tried this with multiple batteries so I don't know what the chances of having 3 different batteries not being able to do it could be.

The test you want done is done with the battery in the vehicle.

Go to www.cruiser54.com and do Tips 1 through 5 before chasing any other rabbits.