My 77, F250 had developed an intermittent electrical, (or at least what I suspect to be an electrical), problem. The truck starts and runs very well but after 15 minutes or so, it just shuts down as if the ignition was turned off. It will almost immediately start again and run well for a while. It's only done this a few times, because after it happened twice I wasn't about to go out on the road again. I have let it sit and idle, and it has done it once sitting at idle. I'm not a great mechanic, but I suspect the ignition because there just isn't any stuttering or loss of power before it shuts down, and it has done this both at idle and under load. It idles well and has good power until suddenly, nothing. Then it will start right back up. It seems like a bad wire might be the culprit, but I let it idle for the better part of an hour, while I gently wiggled every wire and connection in the ignition system and it never shut down. That doesn't rule out wiring, but I think it reduces the probability of an intermittent short or open circuit being the problem.

Has anyone had a problem like this, or know of a source where I might find a solution?

 

A very intermittent problem like this is very hard to find. If I were you, I would pick some critical spots and temporarily wire in a small light bulb. One of the first places would be the coil +. Run one wire to the coil + and run the other to a good ground. Run the wires though the rear of the hood and tape the bulb to the windshield where you can monitor it.