Missing out and dies when warm

No codes will show but one of the mechanics would have known whats wrong so try another dealer ,i suspect a temperature sensor is giving the wrong information to the computer but as i have never seen one of these vehicles i couldnt tell you what and where sorry about negative answer but ?? now a citreon or a renault i can answer

If you have a carb its chock .If injection its fuel related filters regulator restrictions if fuel flow ect.

you need to check fuel pressure with a pressure gauge to see if its within specs.it should be around 35psi and no lower then about 32psi.your problem sounds like a fuel pressure problem and the pump should be changed as well as the filter, but check to make sure the fuel filter is not plugged as this can also cause a pressure problem.

check your fuel filter and pressure in fuel pump

A common problem with Ford products built in the 1980s is the ignition module mounted on the distributor.
You will need to figure out if it is a fuel problem or ignition problem to proceed.

sounds like the reason it starts and idles fine at start up is your choke is functioning... as your vehicle warms up.. the choke starts to kick off... Inspect your throttle body and idle control motor.

check crank sensor (TDC) - most likely it is a faulty one.

Have you checked the fuel pressure regulator? Lee

check engine coolant temperature when it gets warmer, or at operating temperature, and verify that the temperature gauge is showing warmed up to operating temperature. If the coolant temperature sensor tells the computer the engine is cold it will over fuel and miss and the engine will die. When cooled down it will run fine until it warms up. Also could be coil if it starts missing after warmed up.