An old timer once told me 90-percent of fuel problems are electrical.
Electrical issues will often act like fuel starvation.
I just went on Power Tour, and for one day rode with a guy in a 383-powered Road Runner that was having vapor lock issues. While honkin' down the highway, no problem. When stuck in slow-moving traffic, it'd vapor lock. The night before, during a parade, the fix was to let it cool down, then the problem went away. I wasn't there, but I think they also soaked a shop rag in water and put it on the fuel pump. When I was there, they tried the same thing.
Finally, after the fuel pump was cold to the touch, and the fuel filter up by the carb was, we jumped back in. And under any load, it would cut out again.
That's when I told them what the old man told me.
The coil was horrendously hot. We soaked the rag and laid it on the coil, until the coil was cool. Fired up like a champ and we were on our way.
When you're driving down the road, the air flow through the engine is also hitting the coil, and cooling it enough to keep things running. When you get stuck in traffic, it's a hot day, and the coil is questionable, you end up with "vapor lock" issues.
Try replacing the coil.
-Brad
