No spark out of coil

I have power to the coil from the red and yellow wires. I replaced the coil, the plug, the ingnition modulator on the firewall and the modulator off the key under the steering column. I also replaced the coil wire and rotor and rotor cap yet I still don't have spark out of the coil. I replaced the coil a second time, it ran ok until it cooled down the ran for about a minute, died and not spark again. What can you advise about my problem

thank you for your help