Harms Rebuilt '71 Thermoquad - Wondering Idle, Stalls when Put in Gear

at idle the rods have to stay down.
in Neutral the rods should stay down with gently increasing rpm, to over 2000rpm or more, so long as the manifold vacuum continues to increase.
If the needles pop up when you put it into gear, the engine will flood and stall.

Here's a trick; Just take the springs out. At idle and in neutral, this should cure both problems. If it does, then you know to install weaker springs.