Your rear float is too high.
Its showing lean on the gauge because a misfire always reads lean. The gauge may not be reacting fast enough. If you record it you might see it start to rear rich before it pegs lean and stalls.
He didn't say it was misfiring, you lead him in the wrong direction.
To the OP, I always had problems with holleys and hard stops, I had the opposite problem tho with the carb flooding. It sounds like ur carb is setup too dependent on the front barrels, if it's a 4 corner idle carb try opening the rear blades a little more and getting your idle screws setup properly.
