Guess it must be internal. Short of tearing it down I've followed all the listed suggestions. Two choices, tear it down to put a kit in it or switch to a Holley.
What is the footprint of the intake?
If squarebore, another option would be Carter 9625s or 9635s (NOT 9635sa).
If spreadbore and the e-clone is mounted on an adapter, other options would include a late 1960's or early 1970's Rochester Q-Jet for Chevy 350 OR a Carter TQ 9800s or 9810s.
The e-clones are vacuum-cast (genuine Carters were pressure-cast). The e-clones have had porosity issues. Possibly, this is your problem.
Jon.
