While doubtful, the addition of the PCV valve can potentially lean the mixture depending upon the carburetor or the particular PCV valve being used.  Most Sixties and up carbs are calibrated for PCV valves but those carbs from the Fifties vehicles are not and in those cases, must be recalibrated to give a slightly richer mixture in which to compensate.  The incorrect PCV valve being used can also be a problem.

Lorena, Texas (South of Waco)

The pcv valve was incorrect and was allowing for a large vacuum leak. I was only getting 7 inches of mercury. I replaced the pvc, which get my 17 inches, but this did not improve my situation. Here is a video showing acceleration and stalling with and without a vacuum gauge installed:

And heres the update from yesterday, I show the problem after my question about the exhaust:

Well, one last thought. I've had a lot of problems with the fuel hoses/ethanol/carb combination. The hoses tend to deteriorate on the inside, and little bits of rubber show up in the float bowls, above the needle/seat, etc. I've had this happen even on early '90's EFI cars. Even though the filter was good, this crap ended up in the carb. Sitting seems to make it worse.

You seem to have checked out the ignition and timing, and have the proper PCV now. So maybe a little lean from the PCV, and a little crap in the carb, and it's a lean bog the accelerator pump can't cover. Not an obvious blockage, but just a little here and there till it's too lean. Maybe even blocking part of the power valve circuit, so it only shows up on transition.

Also, after years on keeping the tank full over the winter (in warm and dry Seattle), I now leave the cars about 1/4 full. When I start them in the spring and they don't run quite right, I bring the tank to 3/4 full. Solves the problem. I've even had this happen with cars stored over the summer in Tucson, AZ. The fuel stabilizers don't seem to help as much as they used to. I can only blame this on the ethanol, and it's lower evap rate.

I'd go thru the carb, with a good rebuild kit, and replace all the fuel hoses. Supposedly, modern "fuel injection hose" is not just rated for higher pressure, but also ethanol resistance.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Videos are working now

If the carb is somehow not the issue, I was told that bumping up my timing to 10 degrees before tdc instead of the 6 degrees I have it at now could help. Any thoughts?

The 10 degrees of static advance will be one of the better modifications you can make. Later addition: When extending the range of advance (such as adding 4º to the 6º you started with) it is useful to have a look at the totals. With the stock set-up you are working with, the total of initial and the internal fly-weight advance should sum to about 35º-36º (vacuum line disabled). Many of us have changed the springs (to get a bit more rapid advance increase) and also limited the upper end so that the total doesn't exceed the recommendation. Depending on how aggressive you really want this to be - it can all be in "Early" (say 2500 rpm) or "Late" (3000 rpm) - it depends on how bad the local gas is.After making such a "re-curve" performance in the "economy range" can also cause you to want to reduce the total vacuum advance being applied. In most instances, that can also be adjusted at the vacuum pot by various means.   

 
 Steve Metzger       Tucson, Arizona

It was the carb. Runs great now that its been rebuilt.  Here's a video of me cruising around in her: