Did this problem just start on an existing combination?
Is it an auto or stick?
If an auto have you tried slipping it into neutral when coming to a stop
Another issue that will commonly cause this is the mechanical advance being set too loose (IE: coming in at or just of idle)

When you say RPM makes no difference does that mean it will die even at 1500 RPM?
Might also have a stiffened power valve which they will do over time.
A bit a leakage around the throttle shafts is normal (to a point). The hsafts normally don't wear but rather the baseplate itself.

I would start by verifying the mechanical advance is not coming in to soon. might also want to check the vacuum advance as well if your running it