A few things come to mind at this point.  One, the secondary throttle plates are standing slightly open, essentially a huge vacuum leak that the idle circuit can't overcome.  If it did, the idle speed would be way too high.  Another thing could be clogged idle circuits.  Also, a broken lead in the distributor that intermittently makes and breaks as the vacuum advance moves the point plate back and forth.  Good luck.

John

Just curious as to whether your vacuum line for the distributor is hooked up to ported or direct vacuum? You may have said at which case I just overlooked it.  If hooked to the intake, the vacuum source will be direct vacuum but if hooked up on the carburetor, it could be either depending upon the port being used.

I seriously doubt that the secondaries are trying to open right off of idle regardless of the secondary spring being used.  If you have a later model 4150 or 4160 Holley (you haven’t clarified exactly which carb yet), then the accelerator pump system is at the top of the list of items to check.  At full throttle, there should only be about 0.015-0.020” of additional movement or play before bottoming out the accelerator pump diaphragm.  Any more than this will just require adjusting the spring loaded screw and nut that’s the transition between moving parts and reducing the amount of clearance.  Also related to this is any present free play or looseness in the accelerator pump linkage at idle as this will be a stumble or dead spot whenever throttle opening is initially applied.  But all adjustments for this system are performed with the throttle arm in the full throttle position.

You haven't mentioned what trans you are running, but if it's the original Fordomatic, are you aware that it normally takes off in 2nd gear?  That makes for sluggish acceleration.  Try putting the shift lever in Lo and trying it.  Should be a big improvement in take off.

John

The Pertronix instructions don't warn you to be sure the swivelling point plate you attached the unit to is securely grounded. The point systems have a little braided ground wire that grounds the moveable portion of the point plate to the fixed portion (that hopefully then carries the ground to the engine block). Did you retain the braided jumper when you fitted the Pertronix module? To get the greatest possible spark out of the coil, you want it running on the greatest voltage your "switch" (points or Pertronix) will tolerate and grounding to the best (lowest) ground you can find.

As Pete suggests, cam is likely not the problem but does need to be ruled out so here are more questions.  What’s the specs on the camshaft?  Was it degreed in or just installed counting the links in the chain?  And if degreed in, was more than one cylinder checked?  How’s the manifold vacuum at idle?

           Really difficult to diagnose from words, but I'm begining to smell an electrical issue here. Check, double check and then recheck all the ignition stuff try another coil, make sure nothings loose, or grounding or separating inside the insulation. Quite honestly,most carburettor issue turn out to be electrical.