Set the rev limiter on you Digital 6 to 0. My 408 had a problem with a pop on the hit and immediately after gear changes at the drag strip, it wouldn't do it on the street. I changed plugs, wires, distributor pick up, coil, valve springs and was in the carb several times. Finally at the suggestion of a member here I reset the limiter on my Digital 6 to 0 and the pop went away. The limiter was set at 7200 and I was shifting at 6400, it would pop even with the limiter set at 9900.

If that doesn't help buy/borrow a wide band O2 meter and get the carb dialed in. It sounds like it could be going lean causing the misfire.