I'm having a hesitation or bog at 1800-2000 after recently improving the idle mixture settings. I'm not sure if it's too much gas from the accel pump or not enough.

details:
1973 Nikki carb
1984 12A intake manifold (ported out, shutter valve removed)
1980 engine
all of this in a 73 RX-2

The carb is recently rebuilt. Accel. pump works, has factory pump shot setting (lever is not "vertical" with diaphragm housing as per Stirling.) I've been slowing tuning it with a vacuum gauge getting the idle mixture better and better over the course of the last few weeks. I've yet to attain > 15 in./Hg at 900 RPM though. The engine is quite worn so I may never get stronger vacuum than that.

The engine idles and accelerates well but if I let the RPMs get to right about 1800 and then give it some gas, it bogs. I'm sure it's either too much gas or not enough from the Accel pump . . . how do I figure out which it is? I'm gonna increase the shot per Stirling just to see what happens. If it gets worse, I'll go the other way . . .

thanks for suggestions

 

It could be a sticky mechanical advance on the distributor. that's the only thing I can think of, aside from (here it comes) vacuum leaks.