You've got a couple of possibilities for sure.
Extra fuel leaking in could be a failure such as
Accelerator pump check or power valve - in yoiur case could be due to somehting in th efuel damaging the materials.
or could be simple even loose bowl screws depending on the type of gasket (sticky type moer likely to stay sealed).

Or an overfilling bowl on decel is another possibility.

either due to float setting slightly high or needle sticking,
or related to hot vapor pushing fuel in.

Chrysler mentions that as early as this '63 MTSC
http://www.imperialclub.org/Repair/Lit/Master/188/Page13.htm

But it got more attention in the '70s
http://www.imperialclub.org/Repair/Lit/Master/271/Page13.htm

There's even a kit for it that I started a thread about a few years ago.


edit: How would the car run?
With excess fuel such as overfilled bowl it will flood and die nice and soft as you let off throttle.
or may cough and die at full stop.
with busted PV it may run ok but rich, requiring more pedal to get it to run well.