Ok, the problem does not exist when the engine is not engaged, at any rpm. The problem is not present at any rpm in 1st through third gear. Once you shift into fourth, it does not seem that it is RPM sensitve. Rather when you are accelerating, you feel it lagging / jerking / missing. Feels like fuel cut to me, but it seems engine load related rather than RPM. RPM's do increase when accelerating, but more slowly than it should, due to the interruption in smooth accel. Same in 5th gear.
I replaced all vac lines running to the intake manifold and MAP sensor. (along with new MAP.)
Note also that there is a random stall when cold. Only happens once in a while. When it does happen, it dies very quickly with no miss, backfire or any other symptoms. It just shuts off. Starts back up and idles fine.
The symptoms don't make sense to me.