Ralph will likely tell you to do what Milton said. Likely the low end is too lean, causing the idle rpms to be too high, which in turn makes your friend set the throttle too low to compensate.

If he richens the low end slightly and opens the throttle butterfly slightly this problem might disappear. Seems counterintuitive, but it works.

I had the same problem on a different engine. It ran perfectly well on the ground and in flight, but I was always losing it on short final (or jockeying the throttle to keep it running). I richened the low end a bit, which significantly dropped the idle rpms, and opened the throttle a bit to compensate, and voila! no more deadsticks.