I vote for compression loss due to valves not fully closed.
I guess adding more fuel didn`t cure the problem. Iac counts seems normal.
On the second log engine is not making good vaccuum, possibly the result of lost compression.

Humid air is heavier and harder to move. It takes more effort to move the same amount of air. It doesn`t seem to have that much impact as you expect. If you suspect engine chocking, enlarging the 8 ports on the intake manifold is better than drilling the bypass hole.


I hope your individual cylinder trims are not off chart. They do contribute to engine surging and stalling.