I have a 1986 ranger with a 2.9 when cold starts fine and will run great all day as long as I don't shut it off if I shut it off its hard to start but once it starts runs rough for a couple minutes then goes back to normal idle and runs fine.

 

Welcome to the forum

Reads like classic TFI module or coil issue

Either can be effected by heat, when running, air is circulating thru engine bay and so is coolant thru the engine.
When you shut off a warm engine the engine bay heats up and so does the TFI module and coil.

When engine finally starts these will start to cool off again, so start working again.

Read here: Ford EEC-IV/TFI-IV Electronic Engine Control Troubleshooting


I did read where a fellow, with similar problem, wanted to test if it was heat related, he carried a plastic bag and drove until engine was hot, and stopped a convenience store or fast food place that has ice machine for cups
It would try to restart and if it didn't he got some ice in the bag then laid it on TFI module for a minute or so then try to restart.
It restarted every time it was cooled off

 

I'll start by testing the tfi module and the ignition coil once I get off work then let you know my results