I am being a bad boy today and farking off at work. It's a nice day, so I brought the car to tweek it a bit.

I believe I have the secondary spring issue worked out and the car pulled as strong as it ever has down the industrial street I work on... with the air cleaner off.

As soon as I put it on, the car goes back to it's sluggish ways. I checked the air horn vacuum flap and it operates smoothly. However, I think I am still pulling enough vacuum during initial acceleration to prevent the flap from opening and starving the car for air.

The current line on the air horn attached directly to the manifold port. About 22 lbs at idle.

Any thoughts?

If you're talking about the flap in the air cleaner, that is/should be attached to the thermal vacuum valve inside the air cleaner and once it gets to temp it allows the flap to open via cutting the vacuum source. So if you have that flapper valve connected directly to manifold vacuum it wont ever stay open except under hard acceleration when vac drops.

Yep, that one.

It is definitely up to temp, but the flap does not open. Just bent the little tab on the 'switch' to get it to open up.

I'll give her another run with the air cleaner on now.

Let us know the results.

Stronger. But now I think I need to re-tune a number of the carb and timing settings.

It's now slowely getting there.

Try just leaving it disconnected, then if it's better/acceptable you know where you problem lies, if there's no change you have to keep looking.