I got a old ford mustang and I have replaced nearly everything on the ignition on it. Okay, i got a 347 stroker engine its a 66 mustang by the way. I just purchased an msd tfi coil, and another msd 6al ignition box. See, when my car runs for about 20 mins up to operating temp it will cut off, or not have any spark, except for when I do a test for the msd 6al box. Iv'e checked all my connections Im getting 12 volts to the msd 6al and my ground is good all the wiring is good. What else could make this thing, not run? It will start everytime from a cold start but it won't start once it heats up. Iv'e replaced all that I know. What else could be doing this? Please as much info as you can send would be helpful.