I have a 79 Spider, that after about a half an hour of driving, the car just dies, and won't restart for about 15 minutes. I thought it was an overheating problem, but all that checks out? Is there an EGR valve that runs hot air back to the carb? Just wondering if that could be an issue? When it dies, it blows a big puff out the Carb? and right before it dies the RPM's drop and is hard to try to keep it running?

lemme git this straight. the temperature gauge reads normal, right?
the engine loses power, then dies, right?
what you are seeing fromthe top of the carb is prolly a little backfire, right?

i'll betcha lunch that the wires from the magnetic pickup are shorting out inside the distributor, and the mag-pickup needs to be replaced...

or, the leads to/from the coil are loose, corroded, or intermitant.