Mustang Bog
Bill,
I assume you are using either the 5200, or the DGV in the original orientation...bowl facing front of car..., so what I write is for both/either.
First, make sure you have a correct float setting on the carb.
Second, make sure the Float Bowl needle and seat are clear, so that they allow full flow when the float drops. Sometimes, junk will partially plug the openings.
Third, use a pressure guage to indicate whether you have full pressure both under power, and throughout the corner. If the pick-up goes dry while cornering, the float bowl will not refill properly, and allow the bowl level of fuel to lower. That will give you starvation in the corner (fuel level low enough to expose the main jet to air).
Placement of the pickup in the cell/tank (left or right) will determine what direction turn the starvation will occur in. You didn't mention whether the problem was with full tank, or only with lower levels of fuel. My comments are for lower levels of fuel in the cell.
These are the most common problem areas that I can think of.
Good luck.
Bill