<VV> ignition/carb advise needed

[Devin]

I've been chasing a stumble in my wife's 63 for a while now and am nearing my wit's end.  Hopefully somebody out there will have some thoughts on the matter.

The problem:  At 1200-1800 rpm (approx, no tach) the engine will stumble so bad it will buck the whole car.  This is at light throttle cruising.  It is worst when the engine is cold, but it still happens to a lesser degree when the engine is warm.  

What I have done:  
Carbs:  Checked choke linkage, works freely.  Set idle mixture to highest rpm.  
Ignition:  Checked timing.  14 degrees initial.  Checked against factory manual, calls for 32 degrees total, including vacuum advance.  Vacuum advance is not hooked up, checked it recently and it does not work.  Advanced total timing to 32 degrees.  This made the stumble nearly disappear for a few days, then it returned.  Put timing back down to 14 initial.  Pulled cap and inspected.  Found some corrosion on the inside of the cap.  Cleaned this off.  Removed, cleaned and inspected the points.  They were pitted some, filed them and re-installed.  Now when I set the points to .016 gap, factory spec, used, I have 45-48 degrees of dwell, instead of 31-34 degrees it calls for.  I have not yet pulled and inspected the plugs.  A full tune-up was done about 2 years ago, about 8k miles back.  Cap, rotor, points, condensor, wires, plugs and air filters were replaced and carbs were rebuilt.

By the way, this is a 102 HP engine and 4 speed trans.  I drive it to work a few days a week, 40 miles round trip, 18 miles in each direction freeway at 70-75 mph.  Doing this I'm getting 20 mpg.  I would think I should be doing better than that.

Devin