If you have a standard engine, heat shouldn't be a problem, provided the mixture and timing is correct and the carb. heatshield is in place. Maybe the engine is running lean. My present car was giving me a headache because it was a turbo with lots of power. Now it's a normal aspirated lightly tuned engine with about 90bhp. I have the oilcooler and the oil stays steady at 75-100 degrees c. But the hole in the bumper also supplies air to the air filter just below the rh headlamp and another hose presently ends just inside the engine bay. But I am planning to reconnect it and then let it run around the block to the exhaust manifold. I don't like insulation wrapping because it causes metal fatigue in the exhaust.
I don't have pics on internet, but on my video's you can see the hoses:
https://www.youtube.com/watch?v=baRdpotWTQAThey run behind the bumper and via holes I cut below the indicator lights enter the engine bay.
But again I suspect an electric failure in the coil or distributor as suggested earlier in this thread. Standard 1.1 and 1.3 engines hardly cause heat problems in a Midas.