1st Gen / Ed

My 85 has a very random issue which seems like a vacuum leak or carb problem. It is only evident on initial throttle when pulling away from a dead stop. Engine wants to fall on it's face. Otherwise the thing runs great! So here is what Ive done to fix it:
1. Rebuilt carb according to mazda service manual / Accel pump squirts good
2. Replaced all vacuum hoses (and the large hose to the #2 AAV which was bad!)
3. New fuel filter and added a second screen just before carb.
4. new cap and rotor / ignitors are good.
5. new spark plugs and wires.
SMOG test showed higher than average HC but also high NOx which may mean too much air (vacuum leak)?? This problem shows up more when the "car" is cold. Not the engine temp. It also doesn't do it every time, very random! Anyone else have this issue, please chime in I'm stumped.