I'm going to say it is not a Bolt problem. I had a similar problem 15 years ago in a 1973 VW Beetle.
Long story short, I was driving it in January from NJ to Miami. I changed the oil and adjusted the valves laying in snow, and I cleaned some acorns from the area under the crank pulley without thinking about it. As I drove south, it naturally got warmer. By Georgia (55-60 degrees F), I noticed that it felt like hesitations at my top speed of about 75-80 mph, and I noticed some black soot buildup. By Jacksonville (65 degree F), I decided to replace plugs and wires. By West Palm Beach (75-80 degrees F), I couldn't get it above 60 mph, the sound had changed, and when I checked on it at a gas station, it was literally sizzling around the engine block and oil seemed to be seeping from everywhere. I showed up in Miami on a flat bed tow truck.
I adjust things here and there, changed the muffler to relieve back pressure, cleaned the carburetor. No avail. Finally, I dropped the engine, took off the cooling tins, and found fur, pine needles, and toasted acorns tucked into the cooling fins around cylinder 3. I had warped the cylinder heads and needed a valve job. It still runs fine to this day, and I have the nest in a ziplock bag in the trunk!
So it wasn't electrical, but it was a rodent of some sort finding a comfortable habitat in my car that caused serious problems just like yours!