I have a 65 mustang 6 cyl 200. I replaced the carburetor, and the modulator valve. Also installed electric pickup (removed points). The problem is after it's hot and sets turned off for a few mins it stalls when select to drive or reverse. Does not want to take gas. The engine is original never rebuilt with 88K mi. Any suggestion as to what I'm missing or adjustments to look at.
My educated guess would be that the problem is gasohol.
You know that gasohol makes the engine "work harder" to do the same amount of work, hence generates more heat, and that it also boils at a lower temp than "pure" gasoline (the definition of a "viscous cycle").
Now, think about how those Ford 1100 accel. pumps "hang over" on the outside of the carburetor --- they are absorbing more heat than the fuel mass inside the bowl is! So while the engine may not be getting hot enough to boil the gasohol in the bowl, it might just get the comparatively tiny mass of fuel in the accel. pump hot enough to percolate like crazy.
Solutions: use ethanol-free fuel if available; reduce engine temperature (lower heat range plugs & thermostat, bigger fan and radiator, retard the timing, electric fan that continues to cool after engine shut-down) or a heat shield under the carburetor.
What else it might be:
Fuel level in bowl too low to allow accel. pump to "draw" from the bowl (usually due to the misconception that setting the float lower than specified will "stop the carb from flooding");
Accel. pump leaking externally due to warpage in pump cover (common);
Incorrect size check balls (or correct size balls not seated properly) in accel. pump intake and discharge positions;
Inadequate accel. pump jet diameter for gasohol (I always oversize 'em .001 - .002").