well, this just gets more and more interesting!
Just to be clear
The clutch lever pushes fluid down the pipe which then pushes through the slave cylinder onto the rod which opens the clutch
When you release the lever, the clutch springs push it closed, pushing the rod into the slave cylinder and forcing fluid back up to the master cylinder and pushing the plunger back out
The plunger screw position fixes where the aperture is that allows fluid to return back to the master cylinder. Hence, if it's too far in, the clutch can't push fluid back up, can't close properly and ends up slipping.
If there is air in the system, then when you pull the lever in, you compress the air, thus you don't push enough fluid, thus you don't open the clutch completely and it drags, typically making you stall.
However, it would be very surprising to have the symptoms of clutch slip and clutch drag at the same time!
if you have tried screwing outwards the plunger, and also bled the system (easy compared to brakes) and still have problems, I actually would start to worry maybe you have a broken clutch, since before my proper entire clutch explosion, it was dragging and stalling.
let us know....!!