accelerator pump issues
I'm having the exact same issue on my car. 72 Dart 225/Auto with 55k miles. No modifications, and everything at least looks stock and unmolested, just from looking.
I also read somewhere else that in older carbs, there's an o-ring on the acc. pump that newer ethanol-based gasoline can swell/distort.
I'll be using the tips here when I get a chance to look at mine closer.
Thanks!