After driving for 30 mintues if i turn off the car it will not restart untill it cools down. Then starts up and runs like a dream. What is wrong?

Radiator cooling fans not working? The ECM is protecting the engine by shutting it down.

Try changing or switching out the distributor. Most likely getting hot and shuts down. Does it crank but no start whenever it stops? May only start when it cools down again.

Sounds like your coolant level might be low. At highway speed you probably have enough coolant and with the air passing thru the radiator keeps the temp down, but at idle not so much. Or depending whether you have a belt drive or electric fan. Belt driven, could need a new belt.

You need to run a fault code test on the electronic engine control module. You can learn how to do that here

this could be a couple of things - you might check to make sure the fan is spinning ok ( it could be going out or not spinning proper ) ,, also check that your water pump belt is at the correct tension, make sure your anti-freeze and water is at the proper ratio, and I know that you said that you replaced the thermostat - but there is a chance that the thermostat is not opening all the way and is restricting water flow. since you also brought up the ' heater blowing cold ' problem, I would say that there seems to be a water cirulation issue -- ( again to the pump or thermostat ).

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car quits after 30 miniutes of run time no enjine codes fuel system is ok enjine will not restart untill i turn the key to the off position but will only run intermitantly untill you lit it cool down then the same thing all over again

Check heat level of your at that time. A sensor is installed in its Radiator, which automatically turn off the vehicle (as the Temperature needle crosses 3/4) until its temperature falls. In case it is true, then; 1) clean its radiator 2) Check the sensor installed in its radiator. (this sensor was not available in 1993 model)

I have the same problem with my bimmer.To find out if the fuel pump problem take fuel pump out and get something kinda nock on the pump put it back in and start the car. It will run but not 1 or 2 days it will die again. You know that mean.Replace the pump.

possible fuel pump. Try spraying starting fluid into breather while someone is cranking engine. if vehicle tries to run it is fuel problem. If not it could be an electrical componet overheating and cooling and restarting. Coils, relays, ecm.

I'd suggest the ignition control module, however I'd have a certified mechanic check it out just in case...