So the problem is that it needed maintenance all along...
Not bypassing the critical fuel and ignition management systems.
(A simple carb rebuild)
This is the very reason why all threads regarding the NB have been removed or should be.

Those systems when maintained and repaired correctly have that engine running with the best performance and MPG.
Bypassing will always cause a loss in MPG. Compared to a properly tuned and operational BBD ecu system.

If performance and MPG is the goal and you can't get the PE system working well, go with a nice Mopar or Howell EFI system. (No belly acheing about money)

SD